Technical Description
for the
OPTRA
Risley Prism Assembly (RPA) Controller
Prepared for:
Customer Information
Prepared by:
OPTRA, Inc
461 Boston Street
Topsfield, MA 01983
(978)-887-6600
Rev. 05
Date: 4/2/2015
3-0387-1 Rev 05
OPTRA
RPA Controller Technical Description
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(Back of Cover Page)
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OPTRA
RPA Controller Technical Description
Revision History
Rev
Date
Description
00
11/05/2009
Initial Release
Based on the RPSA ICD 3-0352-0.
Changes from that include:
 Renamed document
 Removed references to internal interfaces
 Updated Command Port’s baud rate to 57600
bps
01
03/18/2012
Document updates:


02
04/02/2013
Document Updates


03
8/25/2014
12/17/2014






4/2/2015
Added Position/Velocity configuration
selection during initialization processing
Added extended message response option
Updated baud rate
Added RP100 power information
Updated FAQ
Updated angular LSB to 95.873 microradians
Rewrote section 2.1.2 and 2.1.3 to be clearer
Document updates

OPTRA
Updated Table 3-4 to match RPA Data Sheet
Document Updates

05
Updated figure 4-1
Fixed Q&A error
Document Updates

04
Updated LSB to be accurate
General updates based on customer feedback
Updated baud rate to 115200
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OPTRA
RPA Controller Technical Description
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RPA Controller Technical Description
Table Of Contents
1.0 Overview ................................................................................................................................................. 1 2.0 Technical Description ............................................................................................................................. 2 2.1 Interfaces ..................................................................................................................................... 3 2.1.1 Command/Status Port .................................................................................................................. 3 2.1.2 Command Message Format ......................................................................................................... 3 2.1.2.1 Byte 0 – Command Message Header Byte ..................................................................... 3 2.1.2.2 Byte 1 - RPA System Command Byte ........................................................................... 3 2.1.2.3 Bytes 2 thru 5 – Command Data .................................................................................... 4 2.1.2.4 Bytes 6 – Message Checksum ........................................................................................ 6 2.1.3 Command Messaging Examples ................................................................................................. 6 2.1.4 Response Message Format .......................................................................................................... 7 2.1.4.1 Byte 0 – Response Message Header Byte ...................................................................... 7 2.1.4.2 Byte 1 - RPA System Mode Status Byte ........................................................................ 7 2.1.4.3 Bytes 2 thru 5 – Response Data ...................................................................................... 8 2.1.4.4 Bytes 6 thru 9 – Optional prism rotational angle status ............................................... 10 2.1.4.5 Bytes 6 or 10 – Message Checksum ............................................................................. 10 2.1.5 Parallel Port ............................................................................................................................... 10 3.0 Connectors Descriptions ....................................................................................................................... 12 3.1 JP5 User Interface#1 Connector ................................................................................................ 12 3.2 JP4 Factory Test Connector....................................................................................................... 13 3.3 JP3 User Interface#2 Connector ................................................................................................ 14 3.4 J3 Power Connector................................................................................................................... 15 3.5 J2 Optical Head Interface Connector......................................................................................... 16 3.6 J1 Jumper ................................................................................................................................... 16 4.0 Mechanical Layout................................................................................................................................ 17 5.0 Frequently Asked Questions (FAQ) ..................................................................................................... 18 6.0 Acroynms/Glossary............................................................................................................................... 20 OPTRA
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OPTRA
RPA Controller Technical Description
List Of Figures
Figure 1-1 Risley prism beamsteering overview .......................................................................................... 1 Figure 1-2 RPA system coordinate frame and angle definitions .................................................................. 2 Figure 2-1 RPA Functional Processing Architecture .................................................................................... 2 Figure 2-2 Parallel output timing diagram .................................................................................................. 11 Figure 4-1 RPA Controller Board Dimensions ........................................................................................... 17 List Of Tables
Table 2-1 Command Port Interface Details .................................................................................................. 3 Table 2-2 Command Port Serial Messaging Protocol ................................................................................... 3 Table 2-3. Command Message Format ......................................................................................................... 3 Table 2-4. Initialization Message Encoding ................................................................................................. 4 Table 2-5. [Ψ, θ] Message Command Encoding ........................................................................................... 5 Table 2-6. [ALT, ] Message Command Encoding ..................................................................................... 5 Table 2-7. [Vin, Vout] Message Command Encoding..................................................................................... 5 Table 2-8. [In, Out] Message Command Encoding...................................................................................... 6 Table 2-9. Response Message Format .......................................................................................................... 7 Table 2-10. Initialization Message Encoding ............................................................................................... 8 Table 2-11. [Ψ, θ] Message Status Encoding................................................................................................ 9 Table 2-12. [ALT, ] Message Status Encoding.......................................................................................... 9 Table 2-13. [Vin, Vout] Message Status Encoding ......................................................................................... 9 Table 2-14. [In, Out] Message Status Encoding ........................................................................................ 10 Table 2-15. Additional [In, Out] Message Status Encoding ...................................................................... 10 Table 2-16 Parallel Port Interface Details ................................................................................................... 11 Table 3-1. JP5 User Interface#1 Connector Description ............................................................................ 12 Table 3-2 JP4 Factory Test Connector Description .................................................................................... 13 Table 3-3 JP3 User Interface#2 Connector Description ............................................................................. 14 Table 3-4 JP4 Power Connector Description .............................................................................................. 15 Table 3-5 J2 Optical Interface Connector Description ............................................................................... 16 Table 3-6 J1 Jumper Configuration Options ............................................................................................... 16 Table 6-1. Table Of Acroynms ................................................................................................................... 20 OPTRA
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1.0 OVERVIEW
Figure 1-1 illustrates how a pair of prisms can be used to steer a laser beam. The angle off axis (ALT) is
given by the relative rotational angle between the two prisms, and the direction by the rotational angle ()
of the prism pair. For prism pairs of similar geometry, the deviation angle will double when they are in
alignment and will cancel when they are in opposition. Accurate rotational positioning of an individual
prism is accomplished using a motor and angular position feedback in a closed loop servo control system.
The (ALT,) angle pair is converted into a pair of prism rotation angles (in, out), and the controllers
actuate the prism motors to null out the error signal between the commanded rotation angles and the
actual prism angles as read by the angle encoders. The amount of power is quite reduced in comparison to
standard gimbaled systems since the rotating parts are tightly constrained about the rotating axis, resulting
in much smaller motor torques.
Figure 1-1 Risley prism beamsteering overview
OPTRA’s RPA unit accepts and accomplishes formatted beam position and scanning commands. The
system design is based on rotating the optical elements in a prism-pair assembly to steer the beam over a
wide field of coverage as detailed in Figure 1-2. The advantages of this design are compactness, low
susceptibility to vibration, high reliability, and low-costing components.
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Figure 1-2 RPA system coordinate frame and angle definitions
2.0 TECHNICAL DESCRIPTION
Figure 2-1 shows a detailed view of the RPA processing architecture detailing the various interfaces
internal and external to the RPA. The RPA is comprised of three subsystems: the RPA Controller
assembly, the RP-xx Risley Prism assembly (for example: an RP-25), and an interconnecting cable.
Section 2.0 describes each interface. Section 3.0 details the RP Controller board’s connectors and
jumpers. Section 4.0 describes the mechanical layout of the RP Controller board.
Figure 2-1 RPA Functional Processing Architecture
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2.1 Interfaces
2.1.1 Command/Status Port
!
The Command Port is responsible for accepting formatted command messages from the user and in
response, providing status back to the user in the form of formatted status messages. The details of this
interface are described in Table 2-1 and Table 2-2. The following sections describe each byte of the
command and response message. The implementation of this port is accomplished using a portion of
Connector JP3 or JP5 (see section 3.0).
An initialization message must always be sent to the RPA first. This allows the RPA to properly setup
the prism motors, motor mode, parallel port, internal data, and response interface. This process takes ~15
seconds to complete. At which time, the RPA will send a response message back to the user.
Table 2-1 Command Port Interface Details
Interface Protocol :
LVCMOS or RS232 (Jumper selectable via jumper J1 – See
section 3.0)
Messages sent asynchronously as commanded by the user.
Rate :
Table 2-2 Command Port Serial Messaging Protocol
Start Bit
Data Bit 0
Data Bit 1
…
Data Bit 7
Even Parity Bit
Stop Bit
Baud Rate = 115200 bps
2.1.2 Command Message Format
The Command Message is comprised of 7 bytes of information as shown in Table 2-3. Each byte is
described in the following sections. The RPA will always respond to a Command Message with a
Response message.
Table 2-3. Command Message Format
2.1.2.1
Byte
Description
0
Command Message Header Byte
1
RPA System Command Byte
2 thru 5
Command Data
6
Message Checksum
Byte 0 – Command Message Header Byte
This byte signifies the start of an RPA command message and should be set to CBhex.
2.1.2.2
Byte 1 - RPA System Command Byte
This byte indicates the desired RPA System Mode Command of the message. Each bit of the byte is
encoded as follows:
ab00mmmmbin where
a = Add prism rotational angles to response message (0=do not add, 1=add) (See Section 2.1.4.4)
b = Requested Operating Wavelength (0=User Wavelength 0, 1=User Wavelength 1 or Test
Wavelength)
mmmm = Command Mode
The Command Mode options are as follows:
0hex = Perform RPA Initialization
1hex = Command RPA using [Ψ, θ] system pointing angle, [Ψ, θ] status response returned
2hex = Command RPA using [ALT, ] system pointing angle, [ALT, ] status response returned
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3hex = Command RPA using [Vin, Vout] prism velocities, [Vin,Vout] status response returned
4hex = Command RPA using [In, Out] motor angular positions, [In, Out] status response returned
Chex = No command update desired, [Ψ, θ] status response returned
Dhex = No command update desired, [ALT, ] status response returned
Ehex = No command update desired, [Vin,Vout] status response returned
Fhex = No command update desired, [In, Out] status response returned
2.1.2.3
Bytes 2 thru 5 – Command Data
These bytes are defined based on the Command Mode parameter selection in Byte 1 - RPA System
Command Byte (See Section 2.1.2.2).
2.1.2.3.1
!
Command Mode = 0hex (Perform RPA Initialization)
These bytes initialize the RPA to properly setup the prism motors, motor mode, parallel port, internal
data, and response interface. This command MUST be sent to the RPA first for the RPA to operate
properly. The format of bytes 2 thru 5 are detailed in Table 2-4. Please note that an RPA system
initialized for the Position mode will NOT execute a Velocity command message (Command Mode = 3hex
in Section 2.1.2.2) and an RPA system initialized for Velocity mode will NOT execute a Position
command messages (Command Mode = 1hex, 2hex or 4hex in Section 2.1.2.2). In both cases, the system
will still provide a Response Message as usual.
Table 2-4. Initialization Message Encoding
Byte
2
Description
= mmmmppppbin
where:
mmmm = Motor Mode Selection:
0=Position
1=Velocity
and
pppp = Parallel Port Output Mode:
0= [Ψ, θ]
1= [ALT, ]
2= [In, Out]
3
Parallel Port Output Rate (bits 23-16)
4
Parallel Port Output Rate (bits 15-8)
5
Parallel Port Output Rate (bits 7-0)
Parallel Output Rate units = 1 Hz/count (max=100,000Hz)
2.1.2.3.2
Command Mode = 1hex (Command RPA using [Ψ, θ])
When the Command Mode is set to 1hex in the RPA System Mode Command Byte (see Section 2.1.2.2),
Bytes 2 thru 5 are then used to communicate the desired [Ψ, θ] commands to the RPA. Ψ and θ are
represented by 16-bits, two complement notation with units as shown in Table 2-5.
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Table 2-5. [Ψ, θ] Message Command Encoding
Byte Description
2
Ψ position command MSByte
3
Ψ position command LSByte
4
θ position command MSByte
5
θ position command LSByte
Ψ LSB = 95.873 microradians/count
Θ LSB = 95.873 microradians/count
2.1.2.3.3
Command Mode = 2hex (Command RPA using [ALT, ] )
When the Command Mode is set to 2hex in the RPA System Mode Command Byte (see Section 2.1.2.2),
Bytes 2 thru 5 are then used to communicate the desired [ALT, ] commands to the RPA. ALT and  are
represented by 16-bits, two complement notation with units as shown in Table 2-6.
Table 2-6. [ALT, ] Message Command Encoding
Byte Description
2
ALT position command MSByte
3
ALT position command LSByte
4
 position command MSByte
5
 position command LSByte
ALT units = 95.873 microradians/count
 units = 95.873 microradians/count
2.1.2.3.4
Command Mode = 3hex (Command RPA using [Vin, Vout])
When the Command Mode is set to 3hex in the RPA System Mode Command Byte (see Section 2.1.2.2),
Bytes 2 thru 5 are then used to communicate the desired [Vin, Vout] velocity commands to the RPA. Vin
and Vout are represented by 16-bits, two complement notation with units as shown in Table 2-7.
Table 2-7. [Vin, Vout] Message Command Encoding
Byte Description
2
Vin velocity command MSByte
3
Vin velocity command LSByte
4
Vout velocity command MSByte
5
Vout velocity command LSByte
Vin units = 1 RPM/count
Vout units = 1 RPM/count
2.1.2.3.5
Command Mode = 4hex (Command RPA using [In, Out])
When the Command Mode is set to 4hex in the RPA System Mode Command Byte (see Section 2.1.2.2),
Bytes 2 thru 5 are then used to communicate the desired [In, Out] direct motor commands to the RPA.
In and Out are represented by 16-bits, two complement notation with units as shown in Table 2-8
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Table 2-8. [In, Out] Message Command Encoding
Byte
2
3
4
5
Description
In position command MSByte
In position command LSByte
Out position command MSByte
Out position command LSByte
In units = 95.873 microradians/count
Out units = 95.873 microradians/count
2.1.2.3.6
Command Mode = Chex ([Ψ, θ] status response requested)
When the Command Mode is set to Chex in the RPA System Mode Command Byte (see Section 2.1.2.2),
Bytes 2 thru 5 are all set to 0. No command is given to the RPA but the RPA will respond with a [Ψ, θ]
status response message.
2.1.2.3.7
Command Mode = Dhex ([ALT, ] status response requested)
When the Command Mode is set to Dhex in the RPA System Mode Command Byte (see Section 2.1.2.2),
Bytes 2 thru 5 are all set to 0. No command is given to the RPA but the RPA will respond with a [ALT,
] status response message.
2.1.2.3.8
Command Mode = Ehex ([Vin,Vout] status response requested)
When the Command Mode is set to Ehex in the RPA System Mode Command Byte (see Section 2.1.2.2),
Bytes 2 thru 5 are all set to 0. No command is given to the RPA but the RPA will respond with a
[Vin,Vout] status response message.
2.1.2.3.9
Command Mode =Fhex ([In, Out] status response requested)
When the Command Mode is set to Fhex in the RPA System Mode Command Byte (see Section 2.1.2.2),
Bytes 2 thru 5 are all set to 0. No command is given to the RPA but the RPA will respond with a [In,
Out] status response message.
2.1.2.4
Bytes 6 – Message Checksum
This bytes indicates to the RPA that the message was received correctly. It is set to the lower order byte
of the logical addition of Bytes 0 thru 5.
2.1.3 Command Messaging Examples
To initialize the RPA system for Position Command mode and output [ALT, ] data to the parallel port at
a 100KHz rate, the following 7 byte message is sent to the RPA unit:
CBhex 00hex 01hex 01hex 86hex A0hex F3hex
where
CBhex = Message header
00hex = System mode command for Initialization
01 hex = Set Motor Mode to Position commands, and Parallel Port Mode to [ALT, ]
01hex 86hex A0hex = 186A0hex = 100Khz Parallel Port update rate
F3hex = lower byte of the sum of CBhex+00hex+01hex+01hex+86hex+A0hex
To command the system to go to a (Psi, Theta) location of (10, 20) degrees, the following 7 byte message
is sent to the RPA unit:
CBhex 01hex 07hex 1Chex 0Ehex 39hex 36hex
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where
CBhex = Message header
01hex = System mode command for commanding (psi, theta) locations
07hex 1Chex = 71Chex = round( 0.1745329252 (10 deg converted to radians) / 95.873e-6 )
0Ehex 39hex = E39hex = round( 0.3490658504 (20 deg converted to radians) / 95.873e-6 )
36hex = lower byte of the sum of CBhex+01hex+07hex+1Chex+0Ehex+39hex
To command the system to spin each prism at 1000rpm but in opposite directions, the following 7 byte
message is sent to the RPA unit:
CBhex 03hex 03hex E8hex FChex 18hex CDhex
where
CBhex = Message header
03hex = System mode command for commanding velocity
03hex E8hex = 3E8hex = 1000 rpm
FChex 18hex = FC18hex = -1000 rpm
CDhex = lower byte of the sum of CBhex+03hex+03hex+E8hex+FChex+18hex
2.1.4 Response Message Format
The Response Message is comprised of 7 or 11 bytes of information as shown in Table 2-9. Each byte is
described in the following sections. The RPA will always respond to a Command Message with a
Response message.
Table 2-9. Response Message Format
2.1.4.1
Byte
Description
0
Response Message Header Byte
1
RPA System Mode Status Byte
2 thru 5
Response Data
6 thru 9
Optional prism rotational angle status as
requested by the user (See section 2.1.2.2)
6 or 10
Message Checksum
Byte 0 – Response Message Header Byte
This byte signifies the start of an RPA response message and is set to CBhex.
2.1.4.2
Byte 1 - RPA System Mode Status Byte
This byte indicates the selected RPA System Mode Command. Each bit of the byte is encoded as
follows:
000cssssbin where
c = Command Message checksum error
mmmm = Command Mode echo
The Command Mode echo responses are as follows:
0hex = Initialization status
1hex = RPA [Ψ, θ] position command complete, [Ψ, θ] status response returned
2hex = RPA [ALT, ] position command complete, [ALT, ] status response returned
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3hex = RPA [Vin, Vout] velocity command complete, [Vin,Vout] status response returned
4hex = RPA [In, Out] motor positions command complete, [In, Out] status response returned
5hex = RPA error message
Chex = No command update performed, [Ψ, θ] status response returned
Dhex = No command update performed, [ALT, ] status response returned
Ehex = No command update performed, [Vin,Vout] status response returned
Fhex = No command update performed, [In, Out] status response returned
NOTE: All RPA status response messages indicate the status of the RPA system just PRIOR to
the command update.
2.1.4.3
Bytes 2 thru 5 – Response Data
These bytes are defined based on the Mode Status Byte parameter selection in Byte 1 - RPA System
Mode Status Byte (See Section 2.1.4.2).
2.1.4.3.1
Response Mode = 0 (Initialization Status)
These bytes indicate the status of the RPA initialization process. The format of bytes 2 thru 5 are detailed
in Table 2-10.
Table 2-10. Initialization Message Encoding
Byte
2
Description
= mmmmppppbin
where:
mmmm = Motor Mode Status:
0=Position
1=Velocity
and
pppp = Parallel Port Mode STatus:
0= [Ψ, θ]
1= [ALT, ]
2= [In, Out]
3
Parallel Port Output Rate Status (bits 23-16)
4
Parallel Port Output Rate Status (bits 15-8)
5
Parallel Port Output Rate Status (bits 7-0)
Parallel Output Rate units = 1 Hz/count
2.1.4.3.2
Response Mode = 1hex or Chex (RPA [Ψ, θ] status)
Bytes 2 thru 5 indicate the RPA [Ψ, θ] status just prior to the requested command update. Ψ and θ are
represented by 16-bits, two complement notation with units as shown in Table 2-11.
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Table 2-11. [Ψ, θ] Message Status Encoding
Byte Description
2
Ψ position status MSByte
3
Ψ position status LSByte
4
θ position status MSByte
5
θ position status LSByte
Ψ LSB = 95.873 microradians/count
Θ LSB = 95.873 microradians/count
2.1.4.3.3
Response Mode = 2hex or Dhex (RPA [ALT, ] status)
Bytes 2 thru 5 indicate the RPA [ALT, ] status just prior to the requested command update. ALT and 
are represented by 16-bits, two complement notation with units as shown in Table 2-12.
Table 2-12. [ALT, ] Message Status Encoding
Byte Description
2
ALT position status MSByte
3
ALT position status LSByte
4
 position status MSByte
5
 position status LSByte
ALT units = 95.873 microradians/count
 units = 95.873 microradians/count
2.1.4.3.4
Response Mode = 3hex or Ehex (RPA [Vin, Vout] status)
Bytes 2 thru 5 indicate the RPA [Vin, Vout] status just prior to the requested command update. Vin and Vout
are represented by 16-bits, two complement notation with units as shown in Table 2-13.
Table 2-13. [Vin, Vout] Message Status Encoding
Byte Description
2
Vin velocity status MSByte
3
Vin velocity status LSByte
4
Vout velocity status MSByte
5
Vout velocity status LSByte
Vin units = 1 RPM/count
Vout units = 1 RPM/count
2.1.4.3.5
Response Mode = 4hex or Fhex (RPA [In, Out] status)
Bytes 2 thru 5 indicate the RPA [In, Out] status just prior to the requested command update. In and Out
are represented by 16-bits, two complement notation with units as shown in Table 2-14.
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Table 2-14. [In, Out] Message Status Encoding
Byte
2
3
4
5
Description
In position status MSByte
In position status LSByte
Out position status MSByte
Out position status LSByte
In units = 95.873 microradians/count
Out units = 95.873 microradians/count
2.1.4.3.6
Response Mode = 5hex (RPA error message)
In the process of execution, the RPA encountered an error condition. Bytes 2 thru 5 indicate error codes
that typically indicate a hardware error condition. Please record and report this information to OPTRA
for further analysis.
2.1.4.4
Bytes 6 thru 9 – Optional prism rotational angle status
The user can request additional prism motor rotation status [In, Out] to any response message (See
section 2.1.2.2 Byte 1 - RPA System Command Byte for more information). In and Out are represented
by 16-bits, two complement notation with units as shown in Table 2-15.
Table 2-15. Additional [In, Out] Message Status Encoding
Byte
6
7
8
9
Description
In position status MSByte
In position status LSByte
Out position status MSByte
Out position status LSByte
In units = 95.873 microradians/count
Out units = 95.873 microradians/count
2.1.4.5
Bytes 6 or 10 – Message Checksum
This bytes is set to the lower order byte of the logical addition of Bytes 0 thru 5 or Bytes 0 thru 9 when
additional prism rotation data was selected (See section 2.1.2.2 Byte 1 - RPA System Command Byte for
more information).
2.1.5 Parallel Port
The Parallel Port is responsible for continuous output of the user-requested system pointing angles. The
details of this interface are described in Table 2-16. This implementation of this port is part of Connector
JP3 (see section 3.0).
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Table 2-16 Parallel Port Interface Details
Protocol :
Single ended LVTTL signals
Rate :
User selectable via Command Port up to 100 KHz
Name
Description
Source
Dest.
Valid when Parallel Port Mode = 0 (,), set via Command Port :
Pout1
Support
User
Current  state
Electronics
Pout2
Current  state
Support
Electronics
User
Valid when Parallel Port Mode = 1 (ALT, ), set via Command Port:
Pout1
Current Alt state
Support
User
Electronics
Pout2
Current  state
Support
Electronics
User
Valid when Parallel Port Mode = 2 (In, Out) , set via Command Port:
Pout1
Support
User
Current In state
Electronics
Pout2
Current Out state
Support
Electronics
User
Units
Limit/Range
LSB=95.873
microradians
16 bits data word
LSB=95.873
microradians
16 bits data word
LSB=95.873
microradians
16 bits data word
LSB=95.873
microradians
16 bits data word
LSB=95.873
microradians
16 bits data word
LSB=95.873
microradians
16 bits data word
Data output is in a serial/parallel format. Four 8 bit words will be transmitted every 10 microseconds, along with
a clock to indicate when the data words are valid. Figure 2-2 shows a timing diagram of the output data. The
outputs will be single ended LVTTL level signals. Set up and hold times will be approximately 100
nanoseconds.
100 nS
Clock
Data
D0
D1
D2
D3
Mark
D0 is Pout1(15:8)
D1 is Pout1(7:0)
D2 is Pout2(15:8)
D3 is Pout2(7:0)
Figure 2-2 Parallel output timing diagram
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3.0 CONNECTORS DESCRIPTIONS
3.1 JP5 User Interface#1 Connector
Table 3-1. JP5 User Interface#1 Connector Description
JP5
User
Interface1
10 X 2 header 2 mm spacing
FCI 98464
Pin Number
Name
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
NC
M1ENABLE
NC
M2ENABLE
VCC3
LLTXO
VA1
LLRXI
VA2
AXIS1A
VB1
AXIS1B
VB2
AXIS1IND
DGND
AXIS2A
DGND
AXIS2B
DGND
AXIS2IND
OPTRA
I/O
Description
OUTPUT
OUTPUT
POWER
OUTPUT
OUTPUT
INPUT
OUTPUT
OUTPUT
OUTPUT
OUTPUT
OUTPUT
OUTPUT
POWER
OUTPUT
POWER
OUTPUT
POWER
OUTPUT
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Logic 1 when axis 1 PWM amplifier enabled
no connect
Logic 1 when axis 2 PWM amplifier enabled
3.3 volts for test fixture
User RS232 interface
Analog voltage; axis 1 PWM amplifier input
User RS232 interface
Analog voltage; axis 2 PWM amplifier input
Axis 1 encoder AQB (LVTTL)
Analog voltage; axis 1 PWM amplifier input
Axis 1 encoder AQB (LVTTL)
Analog voltage; axis 2 PWM amplifier input
Axis 1 encoder index pulse (LVTTL)
3.3 volt return
Axis 2 encoder AQB (LVTTL)
3.3 volt return
Axis 2 encoder AQB (LVTTL)
3.3 volt return
Axis 2 encoder index pulse (LVTTL)
12
3.2 JP4 Factory Test Connector
Table 3-2 JP4 Factory Test Connector Description
JP4
Factory test
10 X 2 header 2 mm spacing
FCI 98464
Pin Number
Name
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
TMS
TRSTN
TDI
EMU1
VCC3
PMDTXO
TDO
PMDRXI
TCK
TDI1
TCK
TDO2
TMS1
TCK1
DGND
EMU0
REMAMPN
DGND
REMDIS
DGND
OPTRA
I/O
Description
POWER
OUTPUT
INPUT
POWER
INPUT
POWER
POWER
DSP JTAG INTERFACE
DSP JTAG INTERFACE
DSP JTAG INTERFACE
DSP JTAG INTERFACE
3.3 VOLTS FOR TEST FIXTURE
PMD RS232 INTERFACE
DSP JTAG INTERFACE
PMD RS232 INTERFACE
DSP JTAG INTERFACE
FPGA JTAG INTERFACE
DSP JTAG INTERFACE
FPGA JTAG INTERFACE
FPGA JTAG INTERFACE
FPGA JTAG INTERFACE
3.3 VOLT RETURN
DSP JTAG INTERFACE
LOGIC 0 ENABLES REMOTE PWM AMPLIFIER CONTROL
3.3 VOLT RETURN
LOGIC 0 ENABLES PWM AMPLIFIERS
3.3 VOLT RETURN
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3.3 JP3 User Interface#2 Connector
Table 3-3 JP3 User Interface#2 Connector Description
JP3
User
Interface2
Pin Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
OPTRA
26 pin header 0.1 inch centers
3M 2526-6002UB or equivalent.
Name
DOUT7
DOUT6
DOUT5
DOUT4
DOUT3
DOUT2
DOUT1
DOUT0
TC
CLKO
VCCEXT
+15V
LLRX
+15V
LLTX
-15V
LLRXI
-15V
LLTXO
GND
NC
GND
NC
NC
NC
NC
I/O
OUTPUT
OUTPUT
OUTPUT
OUTPUT
OUTPUT
OUTPUT
OUTPUT
OUTPUT
OUTPUT
OUTPUT
INPUT
POWER
INPUT
POWER
OUTPUT
POWER
INPUT
POWER
OUTPUT
POWER
POWER
Description
Parallel word MSB
Parallel word
Parallel word
Parallel word
Parallel word
Parallel word
Parallel word
Parallel word LSB
Parallel word mark pulse. See Figure 2-2
Parallel clock. See Figure 2-2
Voltage for TTL serial port. 5 volts maximum.
Power for user circuits. 100 mA maximum
User TTL serial port input. Voltage set by VCCEXT.
Power for user circuits. 100 mA maximum
User TTL serial port output. Voltage level set by VCCEXT.
Power for user circuits. 100 mA maximum
User RS232 serial port input
Power for user circuits. 100 mA maximum
User RS232 serial port output
Return for +/- 15 V
No connection
Return for +/- 15V
No connection
No connection
No connection
No connection
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3.4 J3 Power Connector
Table 3-4 JP4 Power Connector Description
J3
Power
Input
Molex 22-05-3061
Mating connector Molex 22-01-3067
Pin
Name
I/O
Description
1
2
3
4
+V
+V
VRTN
VRTN
Chassis
GND
Chassis
GND
POWER
POWER
OUTPUT
OUTPUT
Source Voltage (See Note 1)
Source Voltage (See Note 1)
Vss return
Vss return
POWER
Chassis ground
POWER
Chassis ground
5
6
Note: 1.
OPTRA
RP25F
RP25S
RP50F
RP50S
RP100
28V @ 5A
28V @ 7A
28V @ 10A
28V @ 5A
28V @ 5A
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3.5 J2 Optical Head Interface Connector
Table 3-5 J2 Optical Interface Connector Description
J2
Optical
Head
25 pin micro D connector
Airborn MK263-025-445-220S
Pin Number
Name
I/O
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
IND2QUADB2QUADA2VCC5
DGND
OBLACK
ORED
IWHITE
DGND
VCC5
IND1+
QUADB1+
QUADA1+
IND2+
QUADB2+
QUADA2+
DGND
CHASSIS
GND
OWHITE
IBLACK
IRED
DGND
IND1QUADB1QUADA1-
INPUT
INPUT
INPUT
POWER
POWER
OUTPUT
OUTPUT
OUTPUT
POWER
POWER
INPUT
INPUT
INPUT
INPUT
INPUT
INPUT
POWER
AXIS 2 ENCODER INDEX PULSE DIFFERENTIAL SIGNAL
AXIS 2 ENCODER AQB DIFFERENTIAL SIGNAL
AXIS 2 ENCODER AQB DIFFERENTIAL SIGNAL
+5 VOLTS ENCODER POWER
5 VOLT RETURN
AXIS 1 MOTOR DRIVE
AXIS 1 MOTOR DRIVE
AXIS 2 MOTOR DRIVE
5 VOLT RETURN
+5 VOLTS ENCODER POWER
AXIS 1 ENCODER INDEX PULSE DIFFERENTIAL SIGNAL
AXIS 1 ENCODER AQB DIFFERENTIAL SIGNAL
AXIS 1 ENCODER AQB DIFFERENTIAL SIGNAL
AXIS 2 ENCODER INDEX PULSE DIFFERENTIAL SIGNAL
AXIS 2 ENCODER AQB DIFFERENTIAL SIGNAL
AXIS 2 ENCODER AQB DIFFERENTIAL SIGNAL
5 VOLT RETURN
GND
OUTPUT
OUTPUT
OUTPUT
POWER
INPUT
INPUT
INPUT
AXIS 1 MOTOR DRIVE
AXIS 2 MOTOR DRIVE
AXIS 2 MOTOR DRIVE
5 VOLT RETURN
AXIS 1 ENCODER INDEX PULSE DIFFERENTIAL SIGNAL
AXIS 1 ENCODER AQB DIFFERENTIAL SIGNAL
AXIS 1 ENCODER AQB DIFFERENTIAL SIGNAL
18
19
20
21
22
23
24
25
Description
3.6 J1 Jumper
Table 3-6 J1 Jumper Configuration Options
OPTRA
Pin
Connections
1-2
Command Port
Configuration
RS232
2-3
LVTTL
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4.0 MECHANICAL LAYOUT
The details of the mechanical interface are described in Figure 4-1.
Figure 4-1 RPA Controller Board Dimensions
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5.0 FREQUENTLY ASKED QUESTIONS (FAQ)
Are LabVIEW drivers available to assist in software interfacing to the OPTRA RPA unit?
Yes they are. We provide a CD with every RPA purchase. That CD contains useful
documentation, installation instructions, and LabVIEW drivers for commanding the OPTRA RPA
via the RS232 Command Port interface.
Can you give some specific examples of RPA Command Messages?
To initialize the RPA system for Position Command mode and output [ALT, ] data to the
parallel port at a 100KHz rate, the following 7 byte message is sent to the RPA unit:
CBhex 00hex 01hex 01hex 86hex A0hex F3hex
where
CBhex = Message header
00hex = System mode command for Initialization
01 hex = Set Motor Mode to Position commands, and Parallel Port Mode to [ALT, ]
01hex 86hex A0hex = 186A0hex = 100Khz Parallel Port update rate
F3hex = lower byte of the sum of CBhex+00hex+01hex+01hex+86hex+A0hex
To command the system to go to a (Psi, Theta) location of (10, 20) degrees, the following 7
byte message is sent to the RPA unit:
CBhex 01hex 07hex 1Chex 0Ehex 39hex 36hex
where
CBhex = Message header
01hex = System mode command for commanding (psi, theta) locations
07hex 1Chex = 71Chex = round( 0.1745329252 (10 deg converted to radians) / 95.873e-6 )
0Ehex 39hex = E39hex = round( 0.3490658504 (20 deg converted to radians) / 95.873e-6 )
36hex = lower byte of the sum of CBhex+01hex+07hex+1Chex+0Ehex+39hex
To command the system to spin each prism at 1000rpm but in opposite directions, the
following 7 byte message is sent to the RPA unit:
CBhex 03hex 03hex E8hex FChex 18hex CDhex
where
CBhex = Message header
03hex = System mode command for commanding velocity
03hex E8hex = 3E8hex = 1000 rpm
FChex 18hex = FC18hex = -1000 rpm
CDhex = lower byte of the sum of CBhex+03hex+03hex+E8hex+FChex+18hex
I’m commanding the system with correct commands but nothing is happening. What’s wrong?
There could be various reason for this behavior:
OPTRA
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



Verify that the system is correctly powered, a proper connection is made, and a system
response command is received (The RPA will always respond to a command with a
response).
Also check that the power supply to the RPA is rated as listed in Table 3-4.
Recall that the RPA needs to receive an initialization command prior to any
pointing/velocity command.
An RPA system initialized for the Position mode will NOT execute a Velocity command
message (Command Mode = 3hex in Section 2.1.2.2) and an RPA system initialized for
Velocity mode will NOT execute a Position command messages (Command Mode = 1hex,
2hex or 4hex in Section 2.1.2.2). In both cases, the system will still provide a Response
Message as usual.
What is the minimum round trip timing possible with the RPA Command Message interface?
Using a 115200 baud rate (bits per second) to transfer a 7 byte RS232 command message results
in 0.67 ms Command Message transfer time. Similarly, the Response Message is 7 bytes and will
also consume 0.67 ms. Lastly, the embedded processor requires a maximum 0.4 ms to decode
and update the individual prism motors. Therefore, the total round trip time for a command is
0.67 + 0.4 + 0.67 = 1.74ms. However, the system is design such that the reading, processing, and
responses are all independent processes and therefore, the system can respond to messages
received at the maximum transmission rate (every 0.67 ms or ~1500 Hz).
Note that this timing does NOT include the time it takes for the motors to actually achieve the
commanded positions (this time is dependent on the length of the move require to achieve the
new position).
What is the latency of the data in the response message?
The position and/or prism data contained in the response message reflects the state of the prisms prior to
updating the system with the new command information. This data is can be 0.250 ms – 0.4 ms old prior
to transmission back to the user. Using a 115200 baud rate (bits per second) to transfer a 7 byte RS232
response message back to the user results in 0.67 ms Command Response transfer time. The overall
latency of the response data is therefore 0.92 ms – 1.17 ms. When it is received by the user.
I commanded the Parallel Port to 100KHz but an oscilloscope connected to the port indicates dropouts
in the data update. Why?
There is a single CPU that handles both Parallel Port updates and responding to Command
Messages from the user. This system is designed to give priority to Command Messages. Based
on the previous question, a ~2.7 ms dropout will occur in the Parallel Port update in order for the
RPA CPU to respond to the Command Message.
What the allowable maximum Velocity command I can command the OPTRA RPA with?
This parameter is configured on a per system basis.
What do I do if I received an error response from the OPTRA RPA?
Error messages occur very infrequently and indicate a system failure that needs to be brought to
our attention. Please contact OPTRA if you receive an error response.
What if this section did not answer my question?
We constantly update our website with a FAQ section on the RPA page. Please check there and if
your question is still not answered, contact Technical Support at [email protected].
OPTRA
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6.0 ACROYNMS/GLOSSARY
Table 6-1. Table Of Acroynms
OPTRA
ALT
Altitude
bps
Bits per second
DSP
Digital Signal Processor
FAQ
Frequency Asked Questions
FPGA
Field Programmable Gate Array
GUI
Graphical User Interface
LVTTL
Low Voltage TTL
ICD
Interface Control Document
I/O
Input/Output
PMD
Performance Motion Devices
RPA
Risley Prism Assembly
rpm
Rotations per minute
RS232
Standard UART serial port
SCI
Serial Control Interface
SW
Software
XINT
External Interface
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