DAQCard misses TC

[Manfr]

Hello everybody!

I've got the following setup: I use a DC-motor which provides two encoder signals EncA and EncB.
I XOR them in hardware and provide the result to a DAQCard-700 (clk2). The goal is now to set the
counter 2 to a specific value e.g. 30000 in setup mode 0, switch on the motor and as soon as it
has moved 30000 steps, it should be switched off again (using out2). So far everything seems to
work quite fine.

BUT sometimes (approx. 1 out of 8 times) out2 of the DAQCard doesn't go to high after a TC (after
the counter was 0). If I display the counter's state all the time, I can see, that it counts down
from 30000, rolls over to 65535 and counts down again. The second time it reaches 0, it (most
often) stopps. It seems to me like the DAQCard misses sometimes the TC.

I would be grateful for any suggestions on how to solve this problem!

[Jimmie_A.]

Hello!

I haven't found any information regarding customers with similar problems so I am not sure what can cause this I am afraid. The card you are using is quite old however and uses an 82C54 programmable interval timer for its counting and timing and this counter/timer has its limitations. NI-STC, NI-TIO or NI-STC 2 based products have better functionality and more accurate/faster counter.

Regards,
Jimmie A.
Applications Engineer, National Instruments