1. Control System Summary of Changes Since PDR
All the motors, drivers, sensors, switches, etc. have been chosen
Built up a mechanism using typical parts, a slit mask elevator mockup
Designed and built a client/server system in LabVIEW: uses all proposed LabVIEW functions: data sockets, queues, string parsing, analog input, closed loop motion control.
Ran the mechanism at all three proposed levels of control: actuator, mechanism, and system level (with a slit mask searching procedure)
Control System wiring has been completely designed.
PFIS “Generic Mechanism”
Used for proof-of-concept testing
Mar 18, 2003
PFIS CDR

2. Control System Hardware Block Diagram
Control fiber to payload
AC & RS232 from payload back to top hex, for Etalon controllers
3 PFIS cooled electronics boxes inside PFIS structure
Main (Chassis, power supplies)
Box 1 (Slit mask, wave plate, shutter, focus)
Box 2 (Beam splitter, Grating, Filter, Articulation)
Mar 18, 2003
PFIS CDR

3. Control System Power Management and Distribution
SALT Isolator switch provides power to all of PFIS
Within PFIS, PXI & sensors can be powered without power to actuators
Motors and pneumatics are each powered separately
Etalon High Voltage is interlocked with sensors near HV connectors.
Mar 18, 2003
PFIS CDR

4. Control System Status of Electrical Design
All components have been identified and assigned locations:
Main box with PXI chassis, power supplies, digital & analog inputs
Satellite box 1: slit mask, wave plate, focus, and shutter
Satellite box 2: grating, filter, articulation, and beam splitter
Wiring diagrams & interlock logic are complete - ready to buy & build
Each satellite box implements its interlocks with a Programmable Logic Device
All end-of-travel conditions are sensed
We use a “fail asserted” approach: a broken wire looks like a hard limit
Each hardware interlock is backed up by a matching software interlock
The low-level software interlocks are avoided by the configuration state machine
Shutter interface with SAAO detector subsystem is final
Mar 18, 2003
PFIS CDR

5. Control System Heat Budget
Steady-state heat is all in cooled boxes; 400 W is well below PFIS allocation of 1.3 kW
Primary source of uncooled heat is motors
Most motors have very low duty cycle, and are not used during observing; time-averaged power is about 1 W
Exceptions are polarimetric modes - in the high-speed shuffle modes, duty cycle can be very high. For a 25% duty cycle, add 0.8 W for linear and another 0.8 W for circular.
Mar 18, 2003
PFIS CDR

6. Control System Motors and Drivers
8 axes of motion control
2 NI 7334 cards (1 spare)
4 Oriental Motors (with drivers)
2 embedded (OEM) motors
1Slo-syn high torque motor for articulation
1 DC stepper mike for focus
Mar 18, 2003
PFIS CDR

7. Control System Software Block Diagram
Client/server design
Client sends text strings
Server runs mechanisms
3 levels of server software:
actuator level
mechanism level
procedure level
Interlocks are built in at all levels
Mar 18, 2003
PFIS CDR

8. Control System Software State Diagram
Operational complexity has been tamed
Maximum time to reconfigure: spectroscopy to Fabry-Perot Imaging.
This is driven by two mutually exclusive operations
Other operations can be done in parallel
Mar 18, 2003
PFIS CDR

9. Control System Software Development Plan
All LabVIEW: no custom C code needed
Top-down design
Create LabVIEW type-def data base (data clusters & enumerated commands)
Get astronomer and operator feedback on GUI pages & navigation
Rapidly prototype & use GUI
Bottom-up implementation
Code & debug actuator wrappers
Integrate & test actuator wrappers at mechanism level
Assemble mechanism VIs into operational procedures
Document each VI as we go
Use LabVIEW documentation process
Place text boxes on diagram
Configuration management: use LabVIEW version control
Mar 18, 2003
PFIS CDR

10. Control System Software Integration & Test Plan
Match LabVIEW coding sequence to mechanism fabrication
LabVIEW modules are ready as mechanism comes on line
Bench testing of mechanism & control software happen together
Develop mechanism acceptance test procedures during mechanism I&T
Debugged mechanism software modules get used in high level observing procedures
High-level procedures will include short- and long-form test procedures
Mar 18, 2003
PFIS CDR

11. Control System State Transition Table
Table-driven state machine provides 3rd level of interlocks, in addition to hardware interlocks & actuator-level software interlocks
Table prevents PFIS from being driven into a bad state
“State detection” is part of startup & error recovery - figures out what state PFIS is in
Mar 18, 2003
PFIS CDR