Mapping of high voltage addresses

The software described here contains drivers for LeCroy high voltage supplies. There are main frames of type 4032 which have 32 channels each, and there are main frames of type 1440 which may contain up to 16 cards with 16 channels each. Both types of main frames are connected to a CAMAC controller 2132, and they may be daisy-chained. The access of HVs is therefore quite different from anything else: You need to know only one single CAMAC address - that of the controller of the daisy-chain -, but you need the main frame number and the channel number in the appropriate main frame. The CAMAC address is provided via a module identifier in table ELECLOC (table ) as usual, and the module identifier is listed in table DET_CONF in column HV_CTRL for the HV key attribute (see table ). The main frame and channel numbers within the daisy-chain are given in tables which look as follows:

 
Table: HV addresses for two strips of the external plastic wall  

DET_PLA indicates one strip of the FOPI-plastic wall (see table ) which receives its high voltages from LeCroy 1440 main frames. The attributes MFRCRAT, MFRSLOT, and MFRADDR indicate the main frame number in the daisy-chain (1 MFRCRAT 16), the slot number in the frame (0 MFRSLOT 15), and the address in the slot (0 MFRADDR 15). The names of these three attributes are hardwired into the software. MFRSLOT and MFRADDR are converted to a channel number between 0 and 255 for the driver routine. For simplicity of coding, they have to be present for LeCroy 4032 frames as well, although there are no slots in that type of frame, and MFRSLOT and MFRADDR have to be chosen such that they result in the correct channel number.

Remember that MFRCRAT is a scalar, but MFRSLOT and MFRADDR have to be vectors of the same size as the voltages DEM_HV and MSR_HV. See the discussion of the attribute HV_LEN of table  for details.

There is another possibility to control high voltages: The LAND people are using a DAC 1800 as built by the ElEx to drive the NIM HV supply of their Pockels cell. This possibility has been embedded into the general scheme such that the DAC 1800 is entered as 'HV controller' for the appropriate signal, MFRCRAT and MFRSLOT are zero, and MFRADDR contains the address of the TTL level that drives the NIM HV supply.