VeriProx™
Installation Manual
DRAFT Version 1.22
430-0011-P0
TD1135_rev0700
1999, Biometric Identification, Inc.
All Rights Reserved.
BiometricID Warranty Policy
Biometric Identification, Inc. (BII) warrants its products to be free from defects caused by faulty
materials or poor workmanship for a period of one year from date of shipment from BII. BII
makes no warranty that its products are fit for the use or purpose to which they may be put by the
buyer, whether or not such use or purpose has been disclosed to BII in specifications or drawings
previously or subsequently provided, or whether or not BII's products are specifically designed
and/or manufactured for buyer's use or purpose.
BII's liability is limited to replacing, repairing or issuing credit, at its option, for any products that
are returned by the original purchaser during the warranty period. BII's liability on any claim for
loss or damage arising out of the sale, resale or use of any of its products shall in no event
exceed the selling price of the products. The buyer is responsible for making any claims for
shipment damage (evident or concealed) with the carrier. BII must be notified within 30 days of
shipment of incorrect materials.
This warranty is voided if any component, subsystem, or element of the product(s) has been
subject to electrical or physical abuse, tampering (such as opening a sealed housing or removal
of a product serial number tag), or improper operation as determined by BII. This warranty is also
voided for failure to comply with BII's return procedures as given in the BII Technical Support
Guide and outlined below. Any service provided by unauthorized personnel voids the warranty.
BII offers three (3) options to our customers that have a problem with one of our products:
1.) Warranty Service if the unit is covered under either the factory one-year warranty period or
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 1999. Biometric Identification, Inc.
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any extended warranty the buyer may have purchased. 2.) Fee-based Service if the unit is not
covered under a warranty. 3.) Return for credit if less than 30 days from the original date of
shipment. Service can be provided by BII, by BII Authorized Service Representatives, or by BII
Authorized Repair Centers. Contact BII or visit our WWW site (http://www.BiometricID.com) for a
Service Representative or Repair Center near you. No service can be performed without first
notifying BII. At the option of BII or a BII Authorized Service Representative, service may be
performed onsite at the buyer’s facility.
No product may be returned, whether in warranty or out-of-warranty, without first obtaining
approval from BII. No credit will be given nor repairs made for products returned without such
approval as described in the Returned Merchandise Authorization procedure as given in the BII
Technical Support Guide. Products must be returned, prepaid, to a BII service center (no C.O.D.
or Collect Freight shipments will be accepted). The status of any product returned later than 30
days after the issuance of a return authorization will be subject to review. After BII's examination,
warranty or out-of-warranty status will be determined. If, upon BII's examination, a warranted
defect exists, the product(s) will be repaired at no charge and shipped, prepaid, back to the
buyer. If the buyer desires an airfreight or other expedited return, the product(s) will be shipped
collect, charged to the buyer’s account with airfreight carrier, or charged to the buyer’s account
with BII. Warranty repairs do not extend the warranty period. Repair work is warranted for 90
days from the date of shipment. Replacement components are warranted for one year from the
date of shipment. Returned product(s), whether warranty or out-of-warranty, diagnosed as "No
Problem Found" will be subject to a $150 handling charge and will be returned as is, at the
buyer's expense.
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Notices
The Veriprox™ is currently undergoing FCC Class B, CSA and CE Testing in an approved lab.
All agency approvals are expected by Q2 2000. Required compliance agency identification will
appear on the labeling located on the rear panel of the product.
The power supply offered by Biometric ID is CSA approved and UL listed.
FCC
Pending Approval
UL
Pending Listing
ULC
Pending Listing
CE
Pending Approval
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 1999. Biometric Identification, Inc.
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Disclaimer
The instructions in this document have been carefully checked for accuracy and are presumed to
be reliable. BiometricID, Inc. and its writers assume no responsibility for inaccuracies and reserve
the right to modify and revise this document without notice.
It is always our goal at BiometricID, Inc. to supply accurate and reliable documentation. If you
discover a discrepancy in this document, please e-mail your comments to
[email protected], or contact Biometric ID Technical Support at the telephone number
listed below.
No part of this publication may be placed in a retrieval system, transmitted, or reproduced in any
way, including, but not limited to, photograph, photocopy, computer disk or other record, without
prior agreement and written permission from:
Biometric Identification Inc.
5000 Van Nuys Blvd., Suite 300
Sherman Oaks, CA 91403
Phone (818).501.3908
Fax (818).461.0843
http://www.biometricid.com
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Version Notes
Version 1.22: This is the version described in this manual. Fixes a number of problems found in
version 1.1. This version coincides with PIC version 1.22.
Version 1.1: Supports all previous communications channels as well as RS-485 networking,
adjustable baud rates for RS-232 and for RS-485, and Wiegand enhancements such as the
ability to send a Failure ID code and site code options.
Version 1.02: This version supports the auxiliary communications port (an RS-232 port available
through the bottom of the unit).
Version 1.01: There are few differences between this and the previous version as far as the
hardware and software. One difference is the change in the color-coding of one pair of wires.
See the description below.
Version 1.0 Beta 3: This is the firmware version on the first Veriprox units produced. These units
were distributed to a small number of firms at trade shows in 1999. These units had a slightly
different color-coding on the Pigtail (as described in Table 2 on page 17). For this small batch of
Veriprox units the Blk w/ Wht (pin 9) and the solid Blk (pin 11) cables were switched.
Future versions of the Veriprox hardware and software may be significantly different than
described in this manual. Please make sure that you are using a manual that correctly coincides
with the hardware version you are installing. Please contact Biometric ID if you have any
questions.
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 1999. Biometric Identification, Inc.
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Trademark Disclosures
BiometricID has made every effort to provide disclosures when using trademarks owned by other
companies. Trademarked designations appear throughout this publication. The publisher states
that it is using the designations only for editorial purposes, and to the benefit of the trademark
owner with no intent to infringe upon that trademark. The following trademarks are found in this
manual:
•
Microsoft™, Windows 95™, Windows 98™, and Windows NT™ are trademarks of the
Microsoft Corporation.
•
Veritest™ is a trademark of BiometricID, Inc.
•
VeriProx is a registered trademark of BiometricID, Inc.
•
MV1100™ is a trademark of BiometricID, Inc.
®
Other trademarks not listed here but used within this document are owned by the respective
companies.
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 1999. Biometric Identification, Inc.
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Table of Contents
BiometricID Warranty Policy ________________________________________________________________________ i
Notices _________________________________________________________________________________________ iii
Disclaimer ______________________________________________________________________________________ iv
Version Notes ____________________________________________________________________________________ v
Trademark Disclosures ____________________________________________________________________________ vi
Table of Contents ________________________________________________________________________________ vii
Introduction______________________________________________________________________________________ 1
About the VeriProx® _______________________________________________________________________________ 2
About this Manual ________________________________________________________________________________ 5
Veriprox Installation_______________________________________________________________________________ 6
Steps in a comprehensive installation _________________________________________________________________ 7
Planning the Installation ___________________________________________________________________________ 8
Component Selection _____________________________________________________________________________ 10
Power Distribution_______________________________________________________________________________ 11
Selecting the Right Power Supply__________________________________________________________________________ 12
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Connecting the Computer _________________________________________________________________________ 13
Mounting_______________________________________________________________________________________ 14
Mounting Template_____________________________________________________________________________________ 16
Device Hook-up _______________________________________________________________________________________ 17
Wiegand Connections ___________________________________________________________________________________ 17
Shield _______________________________________________________________________________________________ 17
RS-485 ______________________________________________________________________________________________ 18
Cabling and Interconnection ______________________________________________________________________ 20
When is an RS-485 network required? ______________________________________________________________________ 20
RS-485 ____________________________________________________________________________________________ 21
RS-485 cable specification _______________________________________________________________________________ 22
Network Topology _____________________________________________________________________________________ 24
Cable Termination _____________________________________________________________________________________ 25
Extending the RS-485 Specification ________________________________________________________________________ 28
System Turn-up Procedures _______________________________________________________________________ 30
Device Configuration Check______________________________________________________________________________ 31
Ground Potential Difference Check ________________________________________________________________________ 32
Installation Guidelines ____________________________________________________________________________ 34
Installation Issues: _______________________________________________________________________________ 34
Network Operation Issues: ________________________________________________________________________ 35
Operational Issues: ______________________________________________________________________________ 35
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References ______________________________________________________________________________________ 36
Biometric ID Contact Information___________________________________________________________________ 38
Notes
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Notes
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Introduction
®
BiometricID presents the VeriProx , an integrated proximity reader with fingerprint verification.
BiometricID's product offerings leverage over 20 years of experience designing systems for the
US Department of Defense. The company's mission is to bring their patented fingerprint
verification technology, once found only in government or military applications, to a wide range of
commercial applications around the globe at a reasonable cost.
The Veriprox prevents unauthorized access via loaned, lost or stolen proximity cards by requiring
that the fingerprint of the person seeking entry match the identity of the cardholder. Its ability to
verify fingerprints in the face of adverse conditions like soil and other contaminants makes the
Veriprox useful for factories, plants, construction sites and similar environments that have
previously been unable to implement biometric-based access solutions.
Fingerprint verification has been around for over 100 years, but during that time it has progressed
from an intensive manual operation to an automated computer operation. The Veriprox
represents the state-of-the-art in fingerprint verification technology. It uses a 100% solid-state
design. There are no moving parts, no optics or lenses, and it provides a variety of
communications means.
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About the VeriProx®
Biometric ID’s Veriprox two-in-one solution combines a self-contained fingerprint verification
package about the size of a business card, with an embedded proximity card reader. The two
technologies are housed together in a modern case that conforms to mullion mount standards. It
is a stand-alone or network reader that stores thousands of templates, performs enrollment and
verification and provides standard communications options that enable
it to be easily incorporated into access control systems.
The Veriprox response time is less than 5 seconds for fingerprint
enrollment and less than one second for fingerprint verification. The
system is compact, versatile, and can be configured for a variety of
configurations. The Veriprox supports the industry-standard Wiegand
interface that can be used to connect the Veriprox to most any door
controller or alarm panel. The unit supports RS-232 for administration
through a PC connection, and it also supports RS-485 for multiple-unit
operation and administration.
The Veriprox uses the latest generation of solid-state (chip) fingerprint
scanners or sensors. This type of sensor is being provided by a variety
of electronics manufacturers and the Veriprox is the only device to be
Figure 1: The
®
VeriProx
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1
compatible with each one – this is Biometric ID’s sensor interoperability .
The Veriprox integrates fingerprint verification with proximity card technology. The Veriprox is
available from Biometric ID with either HID or Motorola Indala proximity technology. The readers
used from these manufacturers are compatible with the industry-standard 26-bit Wiegand format.
The operation of the Veriprox is very simple: a user places or waves their card near the Veriprox
unit, the unit prompts the user to place their finger on the sensor (communication is by means of
a multi-colored light), the Veriprox reads the fingerprint and compares it to a stored record of the
user. If the comparison yields a high degree of match, the user fingerprint is accepted and the
user’s ID number is transmitted to the access control unit over the Wiegand connection. If the
match fails, then either nothing is sent to the controller or a failure code is sent so that the
controller can log failed access attempts. The controller unlocks the door for the user if the user
has access. Therefore, the procedure is simple: present a card, place finger, open door. The
whole process takes less than 5 seconds.
Administration of the Veriprox is also simple. Any number of cards can be set up as Enroll or
Delete cards. These cards are maintained by the system administrator(s) responsible for the
access control system (one or more cards can be kept off-site for added safety). To enroll a new
user within a Veriprox unit, present an Enroll card, verify the fingerprint of an authorized Enroller,
present an unused card, and finally place the finger of the user on the system. The user is now
enrolled in this Veriprox unit. If the installation has multiple Veriprox units you will have to either
1
In order to provide Independent Sensor Interoperability (ISI), the sensors must meet Biometric ID’s ISI standards.
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 1999. Biometric Identification, Inc.
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2
enroll in other units or use software (if the units are connected via RS-485 network ) to transfer
the templates. The User ID will also have to be added to the access control system. Deleting a
user from the Veriprox is just as easy – just use the Delete card instead of the Enroll card and
follow the same procedure.
The Veriprox now also includes an auxiliary port in the bottom of the unit. This auxiliary port
supports RS-232 communications with a host computer. You can use this port to install
templates, manage enroll and delete cards, etc.
2
RS-485 and the auxiliary RS-232 ports were not available on previous versions of the Veriprox.
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 1999. Biometric Identification, Inc.
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About this Manual
We have designed this manual to provide tutorial services to the new installer. Within this manual
you will find information on planning the installation, configuration, physical install, and basic user
operation. While reading this manual, you will learn:
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•
Configuration capabilities of the Veriprox
•
Connection and networking recommendations
•
How to use the Veriprox Administration Software
•
How to configure the Veriprox for operation in an Access Control application
•
Troubleshooting suggestions
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 1999. Biometric Identification, Inc.
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Veriprox Installation
The Veriprox from Biometric ID is designed to be compatible with mullion mount applications.
Mullion mounting is not required, however, and the Veriprox can be mounted on any flat surface.
The installer will want to take into account codes and ordinances that affect the installation.
Biometric ID offers a Veriprox™ Software and Hardware Operation Manual under a separate
cover. This guide describes in complete detail the administration and day-to-day operation of the
Veriprox unit.
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Steps in a comprehensive installation
Every installation is unique. In some cases, the issues are well understood and can be handled
in a standard fashion. In other cases, there are issues that are specific to the installation, and
may not be immediately recognizable. This document attempts to address many of the issues
that you will be faced with during installation. The steps for a successful installation are:
Planning the installation – outlining the different components in the installation,
determining the interconnections between different components, identifying issues specific
to the installation
Component selection
Mounting
Device hook-up
Cabling and Interconnection issues
Power-up procedure
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Planning the Installation
Planning the installation is probably the single most important aspect to a successful installation.
Good planning will be comprehensive, accurate, and adaptable. Planning for an Access Control
installation must consider: the access controller, the door locks, and the readers. Readers
provide a means for the users to request access to a controlled area. The Veriprox is unique
from other readers in that it provides not only verification of the presence of an authorized card,
but it also verifies that the authorized holder is presenting the card.
During the planning phase, you should determine:
How many doors need to be protected?
What type of reader on each door (maybe some doors are internal and don’t require the
added security of the Veriprox)?
If multiple Veriprox units are to be networked, a dedicated PC is recommended to
administer the system. This can be done through RS-232 (primary or auxiliary ports), or
RS-485.
The controller must support standard 26-bit Wiegand to work with the Veriprox units.
Standard 26-bit Wiegand is defined as 8-bit site code and 16-bit ID number.
Does the installation require RS-485 network cabling for template
distribution/management?
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When planning the system, identify all wiring by the signal levels they are to carry. Wires can be
generally separated into the following groups:
1. Power distribution: Wires carry power to devices, door strikes, etc.
2. Data communication: RS485, RS-232, Wiegand, etc.
3. Sensor: Door contact, request to exit push button, alarm input, etc.
Use separate cable/conduit for different signal groups to avoid cross talk. Observe the distance
limitation of each type of signal when planning device placement. Line extenders can be used for
extended distances when required.
Do not run any wires near utility AC power wiring, lightning rod grounding wire, etc. to avoid
externally generated transients. Grounding equipment is required for ESD protection and safety.
Do research on the environment where the equipment will operate. If used outdoors, it may be
necessary to seal the readers or protect the installation with a weather shield.
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Component Selection
Component selection will be based on a combination of customer demands and components
selected to meet customer requirements. We are glad that you are considering or have selected
the Veriprox as part of your system integration. We hope that you find the Veriprox to be easy to
use while offering an unparalleled level of security.
The Veriprox cannot work in a stand-alone fashion, however, and therefore must be part of a
larger system. The Veriprox offers RS-232 and RS-485 communications channels for
communicating with a PC or host controller. It also uses the Wiegand protocol to interface with
Access Control equipment such as door controllers (outputs) or additional readers (inputs).
Therefore, a minimum system would consist of a Veriprox unit mounted on or near a door mullion,
an electric lock, and the door controller. More complex systems may consist of Veriprox units on
multiple doors, each door with an electric door lock, a multi-door controller, a PC to run the door
controller and Veriprox management software. Some installations will require anti-passback
capabilities, and these will typically use standard proximity card readers (compatible with the
Veriprox system) on “request to exit”.
In addition to the hardware components, the installation will contain proximity cards, cabling, and
will likely include a PC, an RS-232/RS-485 converter, and software.
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Power Distribution
The Veriprox as well as other components in the system will rely on power provided to the system
for operation. In a small installation, power may be provided by means of an AC adapter placed
near the Veriprox reader itself. In larger installations, power will be distributed from either a
central source or various sources.
Power to the Veriprox units should be:
•
isolated from other sources
•
filtered
•
protected by means of a uninterruptible power supply (UPD) or battery backup.
When planning a system, know the power requirement of each device. If multiple devices are to
share a common power supply, care must be exercised to avoid excessive voltage loss on the
wires. Voltage loss can lead to communication problems when devices are talking/listening on
different grounds.
Voltage loss is directly proportional to wire resistance and the current the wire carries. Place the
power supply as close to the equipment as possible. Select appropriate wire size for the load.
The Veriprox runs on DC power between 6 and 32 VDC. Power requirements are as listed in
Table 1.
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Selecting the Right Power Supply
Most power supplies in the market
today provide good input/output
isolation, however those which do not
provide isolation (or have hit leakage
capacitance), coupled with accidental
AC power lines interchange, present
serious ground fault problems for
installers. With ground fault, the signal
reference between subsystems may
be 115 VAC apart. If these
subsystems are interconnected, the
large potential difference will cause
equipment damage or personal injury.
We recommend use of isolated power
supplies only.
Table 1: Veriprox Power Requirements
Power requirement:
Input voltage range:
Peak Current:
6 VDC
12 VDC
24 VDC
32 VDC
Current at 6 VDC:
Normal Mode
Idle Mode
Sleep Mode
Startup peak
Programming
3.5 W
6 – 32 VDC unregulated
0.6 A
0.3 A
0.15 A
0.1 A
0.4 – 0.6 Amps
0.280 Amps
0.045 Amps
0.360 Amps
0.520 Amps
All factory supplied power supply assemblies are either switching or regulated linear supplies and
are isolated for safety and to minimize ground loop problems.
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Connecting the Computer
The Veriprox units can be connected to the computer either through an RS-232 communications
link or an RS-485 link.
RS-485 and RS-232 are hardware specifications and software protocol is not specified. It is up to
the system designer to define a protocol suitable for the system. Biometric ID has done this with
the Veriprox system. Detailed information on the software protocol can be obtained by contacting
Biometric ID.
RS-232 communications with the Veriprox unit use Rx, Tx, and GND connections. The primary
communications port is wired through the pig-tail in the rear of the unit. There is also an auxiliary
RS-232 port accessible from the bottom of the unit.
The RS-485 implementation in the Veriprox uses a two-wire, half-duplex communication
configuration. In RS-485 there can be only one master and all other units are configured as
slaves. A master-slave type system has one node that issues commands to each of the “slave”
nodes and processes responses. Slave nodes will not typically transmit data without a request
from the master node, and do not communicate with each other. Each slave must have a unique
address so that it can be addressed independent of other nodes. In the Veriprox system the
computer is the master and the Veriprox units are each slaves on the line. To connect the
computer to the RS-485 transmission line, you must either have a computer with a built-in RS485 transceiver or use a converter attached to the computer’s standard serial port (an RS-232
device). The cable connection includes a differential line (+ and -) and a GND connection.
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Mounting
The Veriprox unit can be mounted to any flat surface. The mounting plate is 2 inches wide, which
is suitable for mounting in a door mullion. The mounting plate hole pattern is also compatible with
single gang box mounting, however, the Veriprox mounting plate is not wide enough to cover the
single gang box or hole it is in. The installer will have to provide a
suitable cover plate. The pig-tail protruding from the rear of the unit
is for connecting the Veriprox to the rest of the system.
Factors in determining the position of the Veriprox on the wall should
include mounting in-line with other switch plates or fixtures,
approximately 54 inches from floor to top of unit (see figure 2),
mounted on knob-side of door, and in accordance with Americans
with Disabilities Act.
Veriprox mounting is very simple. The mounting plate is attached to
the wall or mullion using up to 6 screws to secure it in place (see
figure 3). The Veriprox unit is then attached to the mounting plate
with the 4 screws included.
The Veriprox unit is constructed out of durable ABS plastic. The
mounting plate is also constructed out of ABS plastic, and the
interface between the mounting plate and the Veriprox is aluminum.
This system provides for a very lightweight, yet sturdy system.
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48 – 54”
Figure 2: Positioning the
Unit
 1999. Biometric Identification, Inc.
All Rights Reserved.
4 places
Up to 6
Figure 3: Exploded View of Veriprox Mounting Plate and Veriprox
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Mounting Template
Top
Bottom
Figure 4: Mounting plate template
For mounting into wall anchors, wood or sheet metal use #4 flat head screws (<0.125 inch thread
width, <0.250 inch head width).
For mounting onto gang box, use #6-32 machine screw with flat head.
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Device Hook-up
The Veriprox unit is connected to other components of the integrated system through the pig-tail
wire bundle that protrudes from the rear of the unit. This wire bundle is made up of the
connections described in Table 2.
Wiegand Connections
Wiegand output lines should be connected to the 26-bit Wiegand compatible controller. When
connecting Wiegand output to a controller, you must make that connection using Data0, Data1,
and a common Ground reference. Wiegand input lines can be used for an alternate 26-bit
Wiegand input device.
Shield
The Shield wire is connected to the ESD shield of the fingerprint sensor. This should be
connected in such a way as to make a low-impedance connection to Earth ground. DO NOT
CONNECT THE SHIELD TO POWER GROUND. Improper connections will potentially create
ground loops and may cause damage to the Veriprox and other equipment.
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RS-485
RS-232 and RS-485 are used for communication with a PC running Veriprox compatible
software. RS-485 connections among various Veriprox units should be made by connecting the
(+) and (-) lines of the differential RS-485 in a daisy chain manner. For instance, from Veriprox to
Veriprox, the (+) line from one Veriprox is connected to the (+) line of the next Veriprox and so on;
likewise for the (-1) lines. Additionally, connect the grounds from each Veriprox unit back to the
signal ground connection for the PC.
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Table 2: Veriprox Pigtail Connections
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Pin #
1
2
3
4
5
6
7
8
9
10
11
12
Color
Red w/ Blk
Grn w/ Blk
Org
Org w/ Blk
Grn
Red
Blu w/ Blk
Wht
Blk w/ Wht
Red w/ Wht
Blk
Grn w/ Wht
Signal
Wiegand Out Data 0
Wiegand In Data 0
Wiegand Out Data 1
Wiegand In Data 1
Reserved
Wiegand GND
RS-485 (-)
RS-485 (+)
RS-232 Tx
RS-232 Rx
Power GND
Signal GND
13
14
Blu w/ Wht
Blu
Unregulated input (6-32 VDC)
Regulated input (5 VDC)
15
Wht w/ Blk
Shield
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Connect to
Wiegand Out Data 0
Wiegand In Data 0
Wiegand Out Data 1
Wiegand In Data 1
Wiegand GND
RS-485 (-)
RS-485 (+)
RS-232 Rx
RS-232 Tx
Power return
RS-485 GND or cable
shield
Power (6-32 VDC)
May be used as output
if necessary
Earth Ground
 1999. Biometric Identification, Inc.
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Cabling and Interconnection
Cabling may seem to be a trivial aspect to the installation – typically planning the cabling route
and pulling the cable through the building is the most technical aspect of this part of the
installation. This is true for Wiegand and power wiring considerations, however, if your
installation requires the use of RS-485 communications, then the choice of cable, the cable run
length, the network topology, and termination of the network may be very important aspects that
must not be overlooked.
When is an RS-485 network required?
RS-485 is a networking specification similar to Ethernet, which is used for computer networks.
RS-485 is different from Ethernet, however, and is not compatible with modern computer
networks. This means that you cannot connect the Veriprox unit to Ethernet networks.
RS-485 has two distinct advantages over the more common RS-232. First, it allows you to
connect up to 31 Veriprox units to a PC (the PC will either have to have internal support for RS485 or will require an external RS-232/RS-485 converter available from Biometric ID). Second,
the RS-485 specification allows for cable run lengths up to 4000 feet (1200 meters) at modest
baud rates.
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Table 3: Communication Comparison
Spec
Mode of Operation
RS-485
Differential DC
Coupled
No
4000 ft.
32
RS-232
Single-ended DC
Coupled
No
200 ft.*
2
DC Isolation
Max. Distance
Number of Devices on
one line
Max. Data Rate
56 kbps
56 kbps*
*RS-232 communications distances are dependent on baud rate
(bps). For example, at 9600 baud, a distance of 100 ft. is
possible with shielded cable, but at 56 k-baud (kbps) a
maximum of 20 ft. is recommended.
You will need to implement an RS-485 network in the following circumstances:
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•
You have multiple Veriprox units that must be connected together so that templates can
be distributed among the units.
•
You only have a single Veriprox unit, but it is over 100 feet (30 meters) from the host PC.
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 1999. Biometric Identification, Inc.
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RS-485 cable specification
The Veriprox provides a 2-wire, half-duplex RS-485 interface. The main run cable should be low
capacitance, twisted pair cable, with approximately 120-ohm characteristic impedance. Category
5 rated communications cable is used in Ethernet networks. This cable is 24 AWG, unshielded,
twisted-pair with a shunt capacitance of approximately 16 pF/ft and characteristic impedance of
100 – 120 ohms. This is the recommended cabling for RS-485 communications. In certain
electrically noisy environments, a shielded cable may be required.
It is often hard to quantify if shielded cable is required in an application or not. Since the added
cost of shielded cable is usually minimal it is worth installing the first time.
The total length of the communication cable (adding up all of the segments of the run) must not
exceed 4000 ft (1200 m) as outlined in the specification for RS-485 (see reference 3).
Although the RS-485 specification calls out a maximum cable length of 1200 meters and a
maximum baud rate well above that of the Veriprox, a more conservative system should be
configured for no more than 1000 meters and running at a baud rate of 9600 bits per second.
After the network is configured and is running in a stable manner, the baud rate can be increased
if faster network communications are desired.
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 1999. Biometric Identification, Inc.
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Table 4: Recommended Cable Characteristics
Spec
Capacitance (conductor to conductor)
Characteristic Impedance
Nom. DC resistance
Wire gauge
Conductors/Shielding
Recommendation
<20 pF/ft.
100 - 120-ohms
<5 ohm/1000 ft.
24 AWG stranded
>2 pair (shielded optional)
Figure 3: Category 5 cable for RS-485 Communication
Drops (down leads) to equipment are not recommended, but if required, should not exceed 10
feet and should use the same cable recommended above.
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 1999. Biometric Identification, Inc.
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Network Topology
Communication cables for RS-485 should be laid out in a daisy chain. See figure 3.
Long stubs (T connections) should be avoided because they create discontinuities and degrade
signal quality. If the stub is long, a signal that travels down the stub reflects to the main line after
hitting the input impedance of the device at the end of the stub. This impedance is high compared
with that of the cable. The net effect is degradation of signal quality on the bus. Keeping the stubs
as short as possible avoids this problem. Instead of adding a long branch stub, loop the main
cable to the device you wish to connect.
Figure 3: Network Topologies – STAR and CASCADE (daisy chain)
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 1999. Biometric Identification, Inc.
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DO NOT connect devices in a STAR configuration – this creates long stubs and is a cause for
concern. This configuration usually does not provide a clean signaling environment even if the
cable runs are all of equal length. The star configuration also presents a termination problem,
because terminating every endpoint would overload the driver. Terminating only two endpoints
solves the loading problem but creates transmission-line problems at the un-terminated ends.
A true cascade or daisy chain connection avoids all these problems.
Cable Termination
Most RS-485 buses require termination because of fast transitions, high data rates, or long
cables. The purpose of the termination is to prevent adverse transmission-line phenomena, such
as reflections.
For example, suppose an installation uses 2000 feet of cable. A round trip, then, covers 4000
feet. Using a propagation velocity of 0.66c (two thirds the speed of light – contact the cable
supplier for this value for your cable), one round trip is completed in approximately 6.2 microseconds. If we assume the reflections will damp out in three round trips up and down the cable
length, the signal will stabilize 18.6 micro-seconds after the leading edge of a bit. At 56 k-baud
(57,600 bits per second) one bit is 17.4 micro-seconds wide. In this case, the reflections do not
damp out before more information is being sent, and corruption of information is a potential
problem. Termination will solve this problem as will lowering the baud rate. At 9600 baud, the bit
width is 104 micro-seconds wide, the reflections are damped out much before the center of the
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 1999. Biometric Identification, Inc.
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bit, and termination is not required. Longer cable length and higher baud rates each push the
case for use of termination.
A common mistake is to connect a terminating resistor at each node - a practice that causes
trouble on buses that have four or more nodes. The active driver sees the four termination
resistors in parallel, a condition that excessively loads the driver. If each of the four nodes
connects a 100Ω termination resistor across the bus, the active driver sees a load of 25Ω instead
of the intended 50Ω. The problem becomes substantially worse with 32 nodes. If each node
includes a 100Ω termination resistor, the load becomes 3.12Ω.
R
+12 VDC
R
R
+
Figure 4a: Failsafe Termination
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- (B)
Gnd
Page 26
R
+ (A)
Figure 4b: Passive Termination
 1999. Biometric Identification, Inc.
All Rights Reserved.
Biometric ID recommends that the RS-485 transmission line be terminated at both ends. The
recommended termination at the PC end of the line is called Failsafe termination. This terminator
(shown in figure 4a) ensures that there is a proper bias voltage across the receiver inputs. This,
in turn, ensures that the receiver is in a known state and puts less of a strain on the driver to
provide that bias. This termination is typically built into the RS-232/RS-485 converters and
internal PC add-on boards – you should confirm that such a termination exists, but you likely don’t
have to supply it yourself.
The termination at the opposite end of the transmission line should be parallel (or passive)
termination (see figure 4b). The value of R in figure 4b is chosen to correspond to a proper
parallel termination, RT, and it is chosen to be slightly larger than the characteristic impedance of
the cable, ZO. Over-termination tends to be more desirable than under-termination since overtermination has been observed to improve signal quality. RT is typically chosen to be equal to ZO.
When over-termination is used RT is typically chosen to be up to 10% larger than ZO. The
elimination of reflections permits higher data rates over longer cable lengths.
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 1999. Biometric Identification, Inc.
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Extending the RS-485 Specification
Some systems require longer distances or higher numbers of nodes than supported by RS-485.
Repeaters are commonly used to overcome these barriers. An RS-485 repeater can be placed in
a system to divide the load into multiple segments. Each “refreshed” signal is capable of driving
another 4000 feet (1200 meters) of cable and an additional 31 RS-485 unit loads.
Another method of increasing the number of RS-485 nodes only (not cable length) is to use low
load type RS-485 receivers. These receivers use higher input impedance to reduce the load on
the RS-485 drivers to increase the total number of nodes. There are currently half and quarter
unit load integrated circuit receivers available, extending the total allowable number of nodes to
64 and 128, respectively.
The Veriprox represents a single unit load to the transmission line.
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 1999. Biometric Identification, Inc.
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Termination
Twisted Pair
Wiegand & Power – 4 wires
(Data0, Data1, Power, Ground)
Wiegand Door
Controller (4 doors)
Shield
Signal Ground
RS-485 +
RS-485 Safety Ground
Wiegand Door
Controller (4 doors)
Network
Interface
100 ohm
RS-485/
RS-232
Converter
Computer
Figure 5: Network Configuration
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 1999. Biometric Identification, Inc.
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System Turn-up Procedures
System turn-up must follow a step-by-step procedure. Never wire up a system and apply power
to it all at once. This can turn a potential success into an immediate disaster.
The following steps should be observed:
1. Do not apply power to any units.
2. Check all wiring and device configuration.
3. Disconnect all units from RS-485 communication line.
4. Check for the correct supply voltage before connecting it to any device.
5. Power up the PC running the Veriprox or other software that is designed to work with the
Veriprox readers. The RS-232 to RS-485 converter should also be powered up at this time.
6. Configure the PC software.
7. Check for ground fault between the converter and the RS-485 communication line (see figure
5). Find any faults and clear them if they exist.
8. Connect the PC and converter to the RS-485 line.
9. Power up a SLAVE (Veriprox reader), but DO NOT connect it to the RS-485 line. Verify that
it powers up correctly.
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 1999. Biometric Identification, Inc.
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10. Check for ground fault between this unit and the RS-485 communication line (see figure 5).
Find any faults and clear them if they exist.
11. Connect this unit to the RS-485 line.
12. Verify that it communicates with the PC software.
13. If there are more SLAVES (Veriprox readers), add the subsequent readers by repeating steps
9-11.
Device Configuration Check
Devices must be configured correctly before they can communicate. Common problems include
not correctly selecting RS-485 as the Com Port, mismatched baud rates, and incorrect device
addresses. Each device sharing the RS-485 line must have a unique address.
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 1999. Biometric Identification, Inc.
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Ground Potential Difference Check
Before a device is connected to an RS-485 subsystem, it must be checked for ground fault. An
uncorrected ground fault can damage all devices connected to the RS-485 communication line.
To check if there is ground fault for a new unit, follow the steps below:
1. Apply power to all devices already successfully connected to RS-485 line.
2. Power up a new unit, but DO NOT connect it to RS-485 line.
3. Connect the signal ground of the RS-485 line through a 10 k-ohm current limiting resistor
to the signal ground (see Table 2) of the Veriprox unit. There should NOT be more than
1 volt across the resistor. Otherwise find and clear the fault.
4. Repeat the steps in #3 with each of the RS-485 signal lines (+ and –)
5. Connect the new unit to the RS-485 line only if no ground fault is found.
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 1999. Biometric Identification, Inc.
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AC
Power
Supply
DC
DC
RS-485
Limit
Resis
AC
Power
Supply
DC
DC
Volt
Meter
RS-485
Before connecting devices powered by different power supplies, be sure that
there is no large potential difference between the DC sub-systems. Less than
one (1) volt is normal. If a ground fault exists, it must be eliminated. Check
AC power wiring. Check each RS-485 line independently.
Figure 6: Checking for Ground Faults
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 1999. Biometric Identification, Inc.
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Installation Guidelines
Installation Issues:
o
Use Category 5 cabling for RS-485 network
o
Choose one pair of conductors to use for RS-485 differential connection, other conductors should
be used for Signal Ground (Green with White stripe from VeriProx)
o
RS-232/RS-485 Converter must support “sense data” to switch from send to receive mode
o
Before connecting each unit to the network, do the following:
o
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Configure the VeriProx using the auxiliary port (RS-232) and a PC
Set Network ID to a unique number
Set host port to RS-485
Set host port baud rate to 9600 bps
o
Check each unit/cabling for ground fault before connecting to RS-485 network
o
Each unit should have its Shield Ground (White with Black stripe) connected to Earth
Ground
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 1999. Biometric Identification, Inc.
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o
Once all units are configured and connected to the RS-485 network, the baud rate can be
increased to highest supported rate (some experimentation required)
Network Operation Issues:
o
Do not use auxiliary port when RS-485 network is active
o
Unit will return a “busy” signal (error –4) if communication cannot be processed due to current
processing – usually enroll or verify
Operational Issues:
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o
Cards registered as Command Cards (enroll or delete cards) cannot be used as user cards
o
Only 26-bit cards should be used on the system
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 1999. Biometric Identification, Inc.
All Rights Reserved.
References
(1)
B & B Electronics offers an Application Note on RS-485 devices, system configuration,
and termination.
B & B Electronics
707 Dayton Road
P.O. Box 1040
Ottawa, IL 61350
(815)433-5100
http://www.bb-elec.com/bb-elec/literature/485appnote.pdf
(2)
Robust Data Comm provides services and a vast amount of information at their WWW
site.
Robust Data Comm, Inc.
St. Paul, MN 55112
(612)628-0533
http://www.robustdc.com/rdc_apno.htm
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 1999. Biometric Identification, Inc.
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(3)
The Specification is formally named TIA/EIA-485-A and can be purchased from Global
Engineering Documents:
http://global.ihs.com/cgi-bin/detdoc.cgi?FRITTER=111167&DOCID=6798420
(4)
National Semiconductor provides a number of Application Notes:
http://www.national.com/an/AN/
(5)
Belden Wire and Cable Company offers a variety of cables suitable for RS-485 use and
has a number of technical papers:
http://www.belden.com/products/techpprs.htm
(6)
Alpha Wire Company offers a variety of cables suitable for RS-485 use and has a
number of technical papers:
http://www.alphawire.com/index_4.html
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 1999. Biometric Identification, Inc.
All Rights Reserved.
Biometric ID Contact Information
430-0011-P0
Customer Support
(818) 501-3908
FAX
(818) 461-0843
E-mail Support
[email protected]
On-line Support
http://www.BiometricID.com
Mailing address
5000 Van Nuys Blvd.
Suite 300
Sherman Oaks, CA 91403
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 1999. Biometric Identification, Inc.
All Rights Reserved.
430-0011-P0
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 1999. Biometric Identification, Inc.
All Rights Reserved.
Biometric Identification Inc.
5000 Van Nuys Blvd., Suite 300
Sherman Oaks, CA 91403
Phone 818.501.3908
Fax 818.461.0843
World Wide Web Site: http://www.BiometricID.com