Chapter 2. VMUSBSpecTcl configuration

VMUSBReadout uses a Tcl configuration file to define and configure devices in the VME crate and to select the order in which they are read out for each stack.

Normally one has a primary event stack and a scaler stack however, the hardware, and software, support a total of 8 stacks with differing trigger conditions including front panel, timed and VME interrupts.

By adding a small amount of metadata to the configuration file, the same information can be used by SpecTcl to select the order in which it runs unpacking objects that understand the format of data from each module, and distribute data from each channel into parameters. Furthermore, once those raw parameters are known, the SpecTcl configuration processing creates raw spectra for each parameter that has been defined.

The primary bit of metadata required by VMUSBSpecTcl is Tcl array named adcChannels. This array is indexed by module name and each element contains a list of the parameter names to be associated with the input channels of the digitizer. If a channel is unused, use an empty string (""). If the last several channels are unused you can just supply a shorter list.

The remainder of this chapter are a set of examples that show how you can define the parameters of a CAEN V785 peak sensing ADC module you have named adc. The first example shows how to use a Tcl loop to define parameters named adc.00 through adc.31. The Tcl format command is used to ensure that the channel number has leading zeroes if needed. lappend (list append) is used to construct the list an element at a time each pass through the loop.

for {set i 0} {$i < 32} {incr i} {
    lappend adcChannels(adc) [format adc.%02d $i]
}
            

The next example equivalent to the previous one but much more work to write. Something like this may be needed, however if your parameter names don't occur in sets with some regular pattern (remember that you could have several for or foreach loops all lappending to the same adcChannels element).

set adcChannels(adc) [list adc.00 adc.01 adc.02 adc.03 adc.04 \
                             adc.05 adc.06 adc.07 adc.08 adc.09 \
                             adc.10 adc.11 adc.12 adc.13 adc.14 \
                             adc.15 adc.16 adc.17 adc.18 adc.19 \
                             adc.20 adc.21 adc.22 adc.23 adc.24 \
                             adc.25 adc.26 adc.27 adc.28 adc.29 \
                             adc.30 adc.31                      \
                        ]
            

The next example shows how to declare define the same ADC, if you are not using channels 5 through 9.

set adcChannels(adc) [list adc.00 adc.01 adc.02 adc.03 adc.04 \
                             ""     ""     ""     ""     ""     \
                             adc.10 adc.11 adc.12 adc.13 adc.14 \
                             adc.15 adc.16 adc.17 adc.18 adc.19 \
                             adc.20 adc.21 adc.22 adc.23 adc.24 \
                             adc.25 adc.26 adc.27 adc.28 adc.29 \
                             adc.30 adc.31                      \
                        ]
            

Finally, if you are only using the first 8 channels of the ADC (channels 0-7):

for {set i 0} {$i < 8} {incr i} {
    lappend adcChannels(adc) [format adc.%02d $i]
}