8000DB0706
04/2010
Raleigh, NC, USA
Data Bulletin
Replicating a Retentive Timer
using Twido® Suite Software
Retain for future use.
Overview
This document describes how to replicate a retentive timer using
Twido® Suite software.
The Twido PLC does not have a retentive timer block. However, if you are
converting competitive programs that use this feature, the Twido PLC offers
four system words that can provide the functionality of four retentive timers.
Presumption
This bulletin is written for individuals familiar with Twido Suite software and
networked drives. If you are not familiar with this software or network
operation, please consult your system administrator.
Requirements
The following hardware and software is required:
Hardware
•
Twido PLC—ensure that you have all the Twido PLC components
necessary for your application.
This example uses a Twido modular PLC, TWDLMDA20DRT, which can
have up to seven I/O expansion modules.
NOTE: When ordering, pay close attention to the restrictions regarding
the maximum number of I/O expansion modules for each PLC.
Software
•
Related Documents
Twido Suite software version 1.3 or higher
This bulletin provides instructions for programming the functionality of a
retentive timer. For instructions on using Twido® Suite software, refer to the
documentation listed below.
Title of Documentation
Reference Number
Twido Software Reference Guide, V3.2
TWD USE 10AE
Twido Hardware Reference Guide, V3.2
TWD USE 10AE
Twido Programmable Controls Programming Guide
35011386
Twido Catalog
DIA3ED2041102EN
You can download these technical publications and other technical
information from our website at www.us.schneider-electric.com.
User Comments
© 2010 Schneider Electric All Rights Reserved
We welcome your comments about this bulletin. You can reach us by e-mail
at [email protected].
Replicating a Retentive Timer
Twido® PLC System Bits and Words
Twido® PLC System Bits and
Words
8000DB0706
04/2010
Table 1 describes the system words used for the retentive timer functionality
of the Twido PLC.
Table 1:
Twido System Word for the Retentive Timer Functionality,
%SW76 to %SW79
System
Function Description
Words
%SW76
to
%SW79
Twido PLC Programming
Example
These four words serve as 1 ms timers. The system
individually decrements each timer every ms if they have a
S and U
positive value. This provides four down-counters,
down-counting in ms, which is equal to an operating range of
1–32767 ms. Setting bit 15 to 1 can stop decrementation.
This section contains an example of the steps necessary to program the
system words to function as retentive timers. These steps include:
•
•
•
•
•
Defining the Symbols
Down
counters
1–4
Control
Defining the Symbols
Resetting the Retentive Timer
Starting the Timing Function
Completing the Timing Function
Manipulating the Retentive Timer Accumulation Value
Define the following symbols used for the retentive timer function in this
example.
NOTE: This example uses only the first retentive timer, %SW76.
Table 2:
Symbol Descriptions
Address
Symbol
Description
%M0
TIMER_RESET
Sets the preset value of the retentive timing feature
%M1
TIMER_RUN
Starts the retentive timing feature
%M2
TIMER_DN
Set when the timer finishes counting down
%M3
TIMER_COMPL
Sets the timer's accumulated value to a predefined value
%SW76
TIMER_PRESET The value the timer will count down from
%SW76:X15
TIMER_CTRL
Controls the functionality of the count down feature
Figure 1 shows the defined symbols for this programming example.
Figure 1:
2
Defined Symbols
© 2010 Schneider Electric All Rights Reserved
8000DB0706
04/2010
Replicating a Retentive Timer
Twido PLC Programming Example
Resetting the Retentive Timer
Rung 0, shown in Figure 2, sets or resets the retentive timer preset value for
the first retentative timer, %SW76. Ensure that the value is pulsed into the
system word so that the value is not overwritten until the timer needs to be
reset. If the timer is complete from a previous cycle, the TIMER_DN bit resets.
Test bit %M0 must be replaced with conditions that set or reset the retentive
timer. If a pulse is given while the timer is counting down, the value is reset,
and the timer continues to count down from this reset value. Verify the
functionality and modify as needed.
Figure 2:
Resetting the Retentive Timer
Starting the Timing Function
Bit 15 of the retentive timer stops and starts the timing feature. See Figure 3.
When the bit is energized, the timer stops. When the bit is de-energized, the
timer counts down from the last stored value.
Test bit %M1 must be replaced with conditions to activate the counting
feature.
Figure 3:
Starting the Timing Function
Completing the Timing Function
Figure 4:
Timing Complete
Manipulating the Retentive Timer
Accumulation Value
Figure 5:
When the value of the timer reaches 0, the timer function is complete and a
bit is set. Most retentive timers need to be reset before the timing feature
can be re-initiated. When conditions exist to reset the retentative timer, this
bit will also be reset. See Figure 4.
If conditions permit completion of the timing function early, the accumulated
value can be manually manipulated by setting the value of the retentive
timer to 0. Rung 3, shown in Figure 5, demonstrates this functionality.
Manipulating the Retentive Timer Accumulation Value
© 2010 Schneider Electric All Rights Reserved
3
Replicating a Retentive Timer
Data Bulletin
Schneider Electric USA, Inc.
8001 Knightdale Blvd.
Knightdale, NC 27545
[email protected]
www.us.Schneider-Electric.com
4
8000DB0706
04/2010
Twido® is a registered trademark of Schneider Electric. Other trademarks used herein are the
property of their respective owners.
Electrical equipment should be installed, operated, serviced, and maintained only by qualified
personnel. No responsibility is assumed by Schneider Electric for any consequences arising out of
the use of this material.
© 2010 Schneider Electric All Rights Reserved