DG800/DG900 units seems to have issues with counter implementation:
- About 1 second delay is needed after enabling or disabling the counter.
Otherwise unit stops responding properly (start seeing USB errors).
- Second channel and counter cannot be enabled simultaneously.
Reading output signal duty cycle value didn't always work, since it relied
on old (cached) information about the currently active waveform. Changed to
always query channel status so this won't happen anymore.
No need to duplicate the data type, just allocate enough memory to
hold the variable's value. Shuffle the order of items in the array
size calculation (number of items times the size of an item).
This implements support for Rigol DG1000z series digital signal
generators. Driver provides basic control via channel groups
("1", and "2"). Acquisition returns data from the built-in
frequency counter.
Supported models: DG1022Z, DG1032Z, DG1062Z
[ gsi: added some coding style adjustment ]