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Muon Ancillary Systems Stephen Pate New Mexico State University PHENIX Collaboration Meeting October 1997. Ancillary systems = monitoring and control of environmental variables (temperature, high voltage, gas flow, low voltage, non-safety-related alarms)
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Muon Ancillary Systems Stephen Pate New Mexico State University PHENIX Collaboration Meeting October 1997
Ancillary systems = monitoring and control of environmental variables (temperature, high voltage, gas flow, low voltage, non-safety-related alarms) • The muon detector group will use EPICS, the PHENIX standard ancillary controls system. • High voltages will be handled by an separate, global EPICS database. All other muon ancillary systems are the responsibility of the muon group. • What is EPICS…..
EPICS Experimental Physics Industrial Control System • A distributed system of hardware control. • “Operator Interfaces” (OPI’s), usually workstations, are connected via a “Local Area Network” (LAN) to “I/O Controllers” (IOC’s) resident in VME crates. • A database is created in each IOC. Each record in each database is associated with one channel of hardware in the local VME crate. Changes in the database either reflect or cause changes in the associated hardware channel. http://www.aps.anl.gov/asd/controls/epics/ EpicsDocumentation/WWWPages/EpicsFrames.html
Example: Control of high voltage • Items such as demand voltage, trip current, ramp rates, and maximum voltage are all examples of parameters that must be specified from the OPI. These are requests that the user makes to the hardware. When these items are changed by the OPI, the hardware must be updated. • Items such as actual voltage, actual current, alarm status are all examples of parameters that must be supplied by the hardware. When these values are changed by the hardware, the OPI may need to be updated. • The current values of all these parameters reside in the database of the IOC, the center of all activity.
N.B. Not every VME interface is supported by EPICS! • “supported” = somebody wrote a driver for it • Some supported VME hardware: • XYCOM 16 chnl differential ADC/DAC (~$50 per channel) • XYCOM Binary I/O • CompControl CC121 Arcnet Interface • National Instruments GPIB Interface • For a complete list, see http://csg.lbl.gov/Supported.HW.html. • ONCS wants to minimize the total number of different VME modules in use, in order both to minimize the software effort involved and ease the total volume of spares. • survey users’ needs • provide a set of standard solutions to standard problems
N.B. EPICS is based on a one-to-one relationship between each database record and its hardware channel. IOC Database driver/interface/addressing Hardware channel Multiplexing requires an extra layer of software (read “driver”) which does not presently exist! Be prepared to pay for every channel you ask for.
Muons • We have fairly complete (and fairly large!) channel counts for • tracking and ID. It’s time for implementation studies to begin. • This activity is just beginning in Las Cruces. • Issues: • Do we really need (for example) to make analog measurements of all 592 FEM temperatures? At $50/channel, that’s $30k just for the ADC’s. Then there are the ~1000 voltage and currents measurements in the low voltage supply system... • Are we interested in monitoring only, or also control? Which systems? • Except for the alignment system frame-grabber, it seems that we only require analog I/O (ADC’s and DAC’s) and binary I/O (latches and registers). No fancy interfaces? Did we ignore something? If we settle on the VME modules soon, our work in Las Cruces can proceed.