Set-up parameters

Let's start with an example of the table PAR_CONF that deals with set-up parameters:

 
Table: Configuration table for set-up parameters  

The examples displayed in table  mean the following:

1. SETPAR contains the names of the setup parameters available: the walk adjust, the threshold of the constant-fraction branch of our CFDs, the threshold of the leading-edge branch, the timing of the ECL-output, the demand value of the high voltage, the measured value of the high voltage, and the gains of the TDCs.
   'qdc_id' and 'tdc_id' are a special case: There is only one command that uses SETSPC='loc', the command 'shodet'. This command shows the current values of set-up parameters for a specific detector, and it treats 'loc' as a special set-up parameter: The 'shodet'-command shows the electronics addresses of that detector for all modules that are listed in table 'PAR_CONF'.
2. SETSPC contains sort of an abbreviation for groups of set-up parameters: 'hv' specifies high voltages, 'thr' specifies thresholds, 'wlk' specifies the walk, etc. You are not free to choose SETSPC as you like: 'hv' is mandatory, because it tells the software that the addressing goes via HV-controller and LeCroy-daisy chain instead of a simple CAMAC-address. 'thr', 'wlk', and 'tim' are mandatory, because they tell the CFD driver what to do (see below for details). For the meaning of 'loc', see item 1.
3. SETALL is a fossil from the old days when there were no wild cards: It provides a means to obtain a complete list of set-up parameters by asking for set-up parameter 'all'.
4. KEY_ATTR is the attribute by which that parameter is keyed (= sorted) in your tables: High voltages are probably keyed by detector, i.e. there is a table whose key attribute (= first column) is some sort of detector, and some other column is called DEM_HV or MSR_HV. For such parameters, KEY_ATTR must have the generic value 'signal'. (You must not indicate a specific detector attribute like SIG_LAND here, because there may of course be different detectors which all want to have high voltages!) Leading-edge thresholds of the GSI modules, on the other hand, cannot be set for single channels, but only per module. Therefore it makes more sense to have a list of CFDs (a table whose key attribute is CFD_ID), and to store only one value of THR_LE per module.
5. MOD_TYPE is the module type to which the set-up parameter applies. The first three letters contain a general specification like CFD or TDC. For the high voltages, this column has to be 'mfr' (a remnant of 'main frame') in order to provide the connection with the attribute 'mfraddr'. For constant fraction parameters, one digit in the fourth place of MOD_TYPE distinguishes between GSI constant fractions 8101, for which two time constants can be set via CAMAC, and modules 8102 - 8104 where a second (leading edge) threshold can be set. CFD0 indicates parameters which are common to all types (walk and constant-fraction threshold).
   The first three letters of MOD_TYPE are used in other tables, too. Look at the discussion of table  and of the 'chkloc'- command for details.
6. CAV_RDWR is a flag which tells the software whether the parameter can be both written to and read from the front end (CAV_RDWR = 2, e.g. DEM_HV), whether it is read-only (CAV_RDWR = 1, e.g. MSR_HV), or whether it is not accessible via CAMAC at all (CAV_RDWR = 0, e.g. TDC_GAIN).
7. DRV_MODE is foreseen to contain a 'driver mode' which can be used by some driver routines. As of this writing, it is only used to distinguish between the two time constants for GSI constant fractions 8101. Since these modules are not used in cave B, DRV_MODE is of no practical importance right now.

In principle, there is no reason why you should not call your set-up parameters as you please. In practice, however, the software contains an example of utmost stupidity right now: The specifications 'wlk', 'thr', and 'tim' are hardwired into the routines that deal with constant fraction modules, and from these names, the 'driver mode' is obtained. (We feel very sorry about that and promise to fix it some time.) In addition, the names of the two high voltages DEM_HV and MSR_HV are hardwired into the software for the sake of simpler coding.