HADES MDC Gas Monitor

1. Introduction

The large scale HADES Experiment at GSI uses drift chambers for particle tracking purposes. In order to monitor the gas pressure of the filling gas the MDC Gas Monitor NIM module has been developed. It serves primarily as an interlock for the high voltage in case the pressure is out of its working range. For the remote controlling and monitoring of the pressure, of the interlocks thresholds and of several temperatures of critical electronic components the general purpose board HADControl (aka HADSHOPOMO) is used. This board, designed and developed by the EE department of GSI (M.Traxler) is based on the ETRAX single chip computer by AXIS running Linux.

This projects tasks is

• to monitor via EPICS
  • the temperatures which are read out via single-wire bus protocol
  • the voltage, representing the gas pressure
• to control and monitor via EPICS
  • lower and upper threshold settings for the interlock for the HV supply, which reacts on the gas pressure.

For this purpose the results of several projects of the EPICS and HADES groups at GSI are used.

2. Concept

In general the HADControl board retrieves the temperatures and the voltage of the pressure sensors. For the publication of the data as EPICS process variables a two-step-approach is used to fulfill the requirements:

1. HADControl ↔ DIM ↔ EPICS-DIM Interface ↔ EPICS
   1. The data and controls are published via the DIM protocol as DIM services (services and commands)
   2. Since so far the data are published via strings, especially the temperature data of several sensors are combined into one single string, an intermediate dispatcher/splitter is needed until this functionality is either implemented in the HADControl's DIM server routines or the EPICS IOC reading the data as i.e. waveforms. The dispatcher reads in the DIM service strings provided as a client, splits them up, converts the data to double/integer values which are publishes as new single value DIM server as an DIM servers
   3. Those latter DIM services are accessed by EPICS via the EPICS-DIM Interface on the basis of a device support module for EPICS' analog input and output records.
2. HADControl running embedded EPICS
   • This will replace the former step when EPICS has been successfully implemented on the ETRAX platform.

Within this concept the EPICS Group at GSI provided therefore the tools for DIM and EPICS including the programs for the ETRAX platform

3. Components and contributing projects

3.1. HADControl (aka HADSHOPOMO)

• General Purpose IO Module for SlowControl and small DAQ-systems
• developed at EE department of GSI
• Contact: Michael Traxler
• link: http://www.gsi.de/informationen/wti/ee/elekt_entwicklung/hadshopomo_e.html

3.2. HADSHOPOMO for distributed temperature measurement

• Readout of temperatures from sensors on a 1-Wire^© bus via HADControl (aka HADSHOPOMO)
• GSI summer student program 2006: Giacomo Ortana, Italy
• Supervisor: Michael Traxler
• Documentation:
  • Wiki - page
  • Report: Implementation of a new system for measure the temperature of the MDCs in the HADES experiment: the system is based on the 1-Wire^© protocol provided by Dallas Semiconductors., (local copy)

3.3. DIM

• Distributed Information Management System
• web page: http://www.cern.ch/dim

3.4. Project: DIM on ETRAX chip

• Internship: Martin Feldmann
• Supervisor: Peter Zumbruch
• DIM cross-compiled for AXIS' ETRAX
• based on DIM version: v16_8
• Documentation at Cross Compiling DIM for Etrax

3.5. Project: DIMCross_StringClientServer (development)

• Internship: Martin Feldmann
• Supervisors: Peter Zumbruch, Michael Traxler
• Ordering Party: Michael Traxler
• Redesign: Peter Zumbruch
• comprises 3 parts:
  1. above-named DIM on ETRAX
  2. dimServer
     Implementation of template DIM functionality for the HADControl based temperature readout, providing the data as strings based DIM services
  3. command line tools to read, write and toggle services provided by dimServer
• Documentation on Installation: Cross Compiling DIMCross_StringClientServer Package on ETRAX (similar to DIM on ETRAX)

3.6. DIMCross_StringClientServer (adaption and implementation for needed services)

• Michael Traxler, HADES
• Redesign: Peter Zumbruch

3.7. dispatcher/splitter

• Contact: Peter Zumbruch
• DIM based executable
• mode of operation
  • reads as DIM client the string encoded data provided by (several instances of) dimServer
  • splits up the temperature strings into single data elements
  • publishes as DIM server the data as double value
  • reacts dynamically to new or dead input services
  • converts also other kind of channels
• Contact: Peter Zumbruch

3.8. NIM module: HADES MDC gas monitor

• Torsten Heinz, HADES
• Documentation of the HADES MDC Gas Monitor NIM module

3.9. EPICS-DIM Interface

• Contact/Design: Peter Zumbruch
• EPICS device support module (up-to-now for ai and ao records)
• matches DIM services to EPICS PV and vice versa
• Documentation: Wiki: EPICS-DIM Interface
• Contact: Peter Zumbruch

3.10. Implementation into HADES slow control system

• Burkhard Kolb, HADES
• Joern Wüstenfeld

4. Code and Sources

4.1. Project: DIM on ETRAX chip

4.1.1. Prerequisites

• Installation of Axis Developer Board Service SDK

4.1.2. DIM

• download DIM (newest version) (local: dim_v16r10.zip,dim_v16r8.zip (used for code development))

4.2. Project: DIMCross_StringClientServer (development)

4.3. DIMCross_StringClientServer (adaption and implementation for needed services)

4.4. dispatcher/splitter

4.5. NIM module: HADES MDC gas monitor

• Torsten Heinz, HADES

4.6. EPICS-DIM Interface

• EPICS device support module (up-to-now for ai and ao records)
• matches DIM services to EPICS PV and vice versa
• Documentation: Wiki: EPICS-DIM Interface
• Contact: Peter Zumbruch

4.7. Implementation into HADES slow control system

• Burkhard Kolb, HADES
• Joern Wüstenfeld

4.8. ETRAX

4.9. DIM

5. Status

5.1. Freeze out for Beamtime April/May 2007 on March 19, 2007:

---

-- PeterZumbruch - 01 Aug 2007