CMS HCAL Laser System


CMS HCAL laser system should perform the following tasks:

  1. Operate the neutral density filter mechanics for intensity control

  2. Operate the output commutator to select destination

  3. Operate and monitor the laser itself, e.g. on/off, temp, ...

  4. Interface the laser trigger to an external pulse

  5. Digitize the PIN diode intensity monitors

  6. Provide readout of the PIN responses, filter and commutator - positions

  7. Provide status and error information
This system is a non-intelligent local control interface for laser functions which also provides for high accuracy digitization of the intensity monitors. Some CSR space is needed for communicating status information, storing input information and reporting error conditions such as receiving trigger pulses too close together in time. Loading and retrieving information is via a VME interface.


How to achieve this?



A stand-alone system exists. Its schematic view is shown here:


The target system should look something like:

The chosen way to do it is to put a wrapper around the custom made software and make it communicate with PVSS II API manager. In this way we decouple driver part from SCADA (easier to make changes in one of them without having to rewrite the entire code) and we also reuse the existing driver (why throw away something that works?).

Through the use of SCADA We will also obtain superior alarm handling, trending , GUI etc. characteristics. When the final electronics and TTC system become available, the replacement of the CAMAC and home made triggering system could be done without changing either SCADA part or the driver...