unrealistic settling time

Hi.

I have a Measurement Computing PCI-DAS6025 board, though the question 
may not be specific to the board.

In the User's Guide provided by the company, a settling time of 25 
microseconds was typical for reading two different channels 
consecutively and acquiring good data in the worst case.

I am experiencing with the cb_pcidas64 driver a situation where delays 
much longer have to be introduced. For example with nine volts applied 
to channel 8, and nothing applied to channel 0:

Reading from channel 8: ~9V
Reading from channel 0 to reset
Sleep for 50 microseconds
Reading from channel 0: ~7V

In fact, it isn't until i sleep for around 80 _milli_seconds that i get 
readings that are reasonable. Given the sleep time limitation of 
instruction INSN_WAIT, all of my sleeping is occurring at the user 
level. This seems completely unrealistic.

Has anyone ever encountered this degree of settling requirement before? 
Where might be a place to start investigating.

Thanks,
Noah W

Received on 2005-07-07Z03:37:44