Minutes of HCAL DCS meeting held on Thursday 2001.09.27

For HCAL Internal Use Only

Part A: Discussion of common approach to DCS by EMU/HCAL

S. Sergueev presented current status of HCAL DCS concentrating on potentially common areas. D. Acosta presented a brief overview of areas where EMU group believes that common approach could be beneficial.

Two main areas are HV and LV control and monitoring.

High Voltage:

There are two different approaches in EMU system:

• ME1/1 uses Bulgarian provided HV system which is almost identical to HCAL HV system. Here the overlap is obvious.
• The HV system for the rest of EMU is still not chosen. One candidate is CAEN power supply, another one custom-made by St. Petersburg (Gatchina) institute. CAEN HV power supplies come equipped with OPC server and their interfacing to SCADA is supported by JCOP. Control and monitoring of Gatchina power supplies are still undefined. Possible solution could be a home-made DIM server. The choice of the final HV system will be done on price/performance basis.

Some generic control panels for HV monitoring and control are included in the JCOP Framework. Both candidate power supply systems (CAEN and Gatchina) have four-layers hardware structure and due to this some extra work will be needed to adjust Framework panels to the EMU HV monitoring needs (i.e., Gatchina solution is cheaper than CAEN but requires more custom software.) There is some potential overlap here on the look and feel of the upper level software (i.e. that furthest from the hardware).

Low Voltage Control, and Monitoring

The power generation of LV (probably through 400 Hz AC source and AC/DC converters) is a common basis.

On on-board LV monitoring for HCAL and EMU have significant differences. First, the hardware is also different. The middle level is also different as the communication mechanisms are not the same, as are the partitioning of the objects ("wedge" for HCAL, "chamber" for EMU). Again, the same look and feel can be most easiliy achieved only on the level furthest from hardware.

EMU sends the temperature and low voltage data from on-chamber mezzanin boards through custom made interface into VME crates sitting on the periphery of endcap disks. The crates (64 in total) contain Dynatem-360 VME CPU board running under (reduced version of) LINUX, communicating with the rest of the DCS through Ethernet. An obvious solution would be to implement DIM server on Dynatem. The open question is whether the Dynatems have enough memory/CPU power to ensure correct operation of DIM. Possible candidate for that evaluation is a group from UCR lead by Bob Claire.

S.S. has suggested the possibility of replacing the EMU mezzanine board with HCAL monitoring board.

HCAL had as its baseline option to use micro controller with CAN-bus interface. Unfortunately the micro controller could not work under HCAL conditions and replacing it by the home-made CAN-bus controller requires a lot of work. S.S. has proposed much smaller, simpler and cheaper version of a control/monitoring module. Such a module would rely on minimal, but rad-hard bipolar FPGA and simple, cheap RS 485 interface. The choice between these two systems can be made only after a demonstrator board has been constructed, tested and its correct operation in the rad. field confirmed.

During the discussion several more subjects were addressed:

F. Glegge pointed out that there are commercially available hubs offering transition between a single Ethernet line and multiple serial link ports ( RocketPort ). This hub is certainly an attractive option for HCAL and more detailed information on its structure, rad. hardness and behavior will be necessary.

Alignment is completely out of HCAL scope of activities and the requirements of EMU should be much better addressed through muon community where certain activities in that direction apparently exist (names of Kaori Maeshima and Ivan Vila were mentioned).

Cooling is a CERN/LHC wide project and both HCAL and EMU should use the knowledge obtained by JCOP.

Measurements of magnetic and radiation fields are of common interest for all CMS subsystems and D.L. should check the plans of the integration (mag. field) and safety (rad. field) groups.

[Note added by D.L. after the meeting:
Measurements of both magnetic and radiation fields are in very early stages of planning. There are preliminary plans for measurements of mag. field during magnet tests on surface and no precise plans for measurements during detector operation. Cooridinator inside CMS Integration group is Andrea Gaddi.
First proposal for radiation monitoring will be presented by Barbara Camanzi during TCM #47, scheduled for October 29th, 2001.

Part B: Developments in HCAL DCS

The upcoming test beam in 2002 is a major effort for HCAL community where the CMS-like front-end electronics will for the first time be implemented with real detector and CMS-like readout. Summer 2002 is the only occasion when production wedges of HB and production scintillators of HE can be calibrated in a test beam. This requires detailed and early planning as well as timely and complete preparations.

DCS-wise there are several areas where an effort is needed:

• HV system
  The problem might be expected late (Jan. 2002) delivery of HV crate and controller by Bulgarian group. A workaround is to test the PVSS and custom software on ME1/1 HV crate whose delivery to Dubna has been announced for November 2001. Serguei is to follow up this subject.
• H2 moving table
  Computer based control and monitoring of table position is certainly needed. The control cabinet of the table contains RS 485 interface and Laza will check its specifics and work on its activation. Another subject to pursue is incorrect operation of flashing lights which apparently stems from one broken control circuit. The company producing the circuits has been contacted, but they can start reparations only after highly radioactive HF prototype is removed from H2.
• Beam parameters
  (magnets, collimators, beam files etc) should be included into the run data file. Laza will take care that these data are available either to DCS (more reasonable) or DAQ.
• Beam profile
  Readout of beam chambers (standard SPS delay MWPCs read by a wide range TDC) will most probably be required. There is a CAEN made v767 TDC in H2, but a problem might be that it needs CERN v430 backplane... Solution, an H2 6U+Jaux crate running in parallel with the data-taking 9U crate. We must synchronize this readout with the calorimeter readout (e.g. by splitting trigger signal into one branch going to TTCvi and another one goint into TDC).
• Laser/LED calibration data
  The existing system is based on CAMAC standard and communication with a PC is ensured through GPIB interface. As neither CAMAC nor GPIB are supported by PVSS and none will be used in CMS it looks like an unnecessary waste of time and effort to try to translate the system "as is" from LabWindows into a PVSS based one. The control of laser/LED can be more easily achieved through VME interface and DAQ than DCS. The details of the implementation depend on the final architecture of the DAQ/TTC system which still has a number of open issues.

• Finish DCS work by March CMS week.
• Install DAQ with few channels before/during CMS week.
• DAQ fully available for middle of April 2002, the expected start of SPS operation.

• Will H2 test beam or NA 49 fixed target experiment be the first user?
• Can we really have enough hardware for all channels (and how many is enough)?
• Will we be testing HE? HF?