Fixed-size arrays vs. variable-size malloc'ed arrays for waveforms

[jspring@csg.lbl.gov (John Spring)]

Hi there:

I'm trying to display a waveform using EPICS. I've gotten the state
sequencer to save the data into a file, but I cannot seem to display
it. Timestamps are working. I get the error message

sydCAFunc: error on ca_array_get_callback(GR) for WAVEFORM_ARRAY.VAL :
Count requested inappropriate for that channel
sydCAFuncConnHandler: error finishing connection for WAVEFORM_ARRAY.VAL

but the count should be initialized to zero. Does anyone have a short
program illustrating the proper way  to display a waveform? Maybe there's
something incorrectly set in gdct or edd. 

Also, do I *have* to use fixed-size arrays for waveforms? Can't I use
a pointer and the C functions calloc and free to vary its size?

Thank you very much.

John Spring