A Very Simple First Algorithm - HP VXI 75000 C Series User's And Scpi Programming Manual

Algorithmic closed loop controller
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NOTES

A Very Simple First Algorithm

128 Creating and Running Custom Algorithms
5. Re-define one of the algorithms with swapping enabled and specify
<swap_size> at least as large as the value from step 3 above (and
probably somewhat larger because as alternate algorithms declare
different variables, space is allocated for total of all variables
declared).
6. Swap each of the alternate algorithms for the one defined in step 5,
ending with the one you want to run now. Remember, you don't send
the <swap_size> parameter with these. If you don't get an "Algorithm
too big" error, then the value for <swap_size> in step 5 was large
enough.
7. Define any other algorithms in the normal manner.
1. Channels referenced by algorithms when they are defined, are only
placed in the channel list before INIT. The channel list cannot be
changed after INIT. If you re-define an algorithm (by swapping) after
INIT, and it references channels not already in the channel list, it will
not be able to access the newly referenced channels. No error
message will be generated. To make sure all required channels will be
included in the channel list, define <alg_name> and re-define all
algorithms that will replace <alg_name> by swapping them before
you send INIT. This insures that all channels referenced in these
algorithms will be available after INIT.
2. The driver only calculates overall execution time for algorithms
defined before INIT. This calculation is used to set the default output
delay (same as executing ALG:OUTP:DELAY AUTO). If an
algorithm is swapped after INIT that take longer to execute than the
original, the output delay will behave as if set by ALG:OUTP:DEL
0, rather than AUTO (see ALG:OUTP:DEL command). Use the same
procedure from note 1 to make sure the longest algorithm execution
time is used to set ALG:OUTP:DEL AUTO before INIT.
An example program file named "swap.cs" on the examples disc shows how
to swap algorithms while the module is running. See Appendix G page 389
for program listings.
This section will show you how to create and download an algorithm that
simply sends the value of an input channel to a CVT element. It includes an
example application program that configures the HP E1415, downloads
(defines) the algorithm, starts and then communicates with the running
algorithm.
Chapter 4

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