I'm writing a multi-channel PI controller using the PID vi (in the PID toolkit). All channels will have the same setpoint, output range and PID tuning values. In the help file for the PID vi it say:
"The DBL Array instance of this polymorphic VI can be used in
multi-loop PID control applications. In this case, the length of the primary
input array will determine the length of the output array. Other input arrays do
not necessarily need to be the same length as the primary input array. Other
input arrays will be resized by this function to the same length as the primary
input array as follows:
- If the input array is longer than the primary input array, the input array
will be truncated to the length of the primary input array. Additional values in
the array are not used.
- If the input array is shorter than the primary input array, the last value
of the input array will be repeated until the size matches that of the primary
input array.
In this manner an input value that should be used for each output
calculation does not need to be specified repeatedly in the array passed into
this function. Instead, the array can consist of a single value which will be
used for each output calculation."
>>I take this to mean that I don't have to laboriously repeat the same data for every channel; ie. I can wire a 14-way array to the 'process variable' input of PID.vi but only eg 1 number to the temperature setpoint etc. In practice, however, this doesn't work. See attached vi (NB this is not yet complete so you can't run it!) and note the broken wires!
Dave
