I am counting TTL inputs from two counters of my PC-TIO-10 but the first one starts from 65535 instead of zero.

[yamanalp]

I have an quadrature encoder with A,B and Z phases. I do not use Z yet. PC-TIO-10 does not have up-down counter so I use two counters two measure the angle with its orientation. I use A as a source of the 1.counter and the gate of the 2. one, and B as the gate of the 1. one and the source of the 2. one.
I read the values but 1. counter usually starts from 65535 instead of zero and decrease. These counters are of different Am9513 chips on the board. I wonder whether the problem is sourced from the hardware or my program.. My computer is Pentium 166, 32 Mb RAM. I also wonder if it can cause a problem.
My vi's are attached and maybe somebody can help m
e. very thanks..
Alper Yaman

[Filipe A.]

Hello;

That's strange. That number is the exact number that the counter will count up to, before rolling over back to zero. Try to reset the counter, through a VI, before you actualy start the counting operation. I wonder if that particular counter is presenting some sort of hardware failure.

Regards
Filipe A.
Applications Engineer
National Instruments

[yamanalp]

Last night, I did the things that you said. When I use 6. and 7. counters, it gives no error anymore. When I use 3. and 6. counters, it rarely gives that error. I was using 1., 2., 3. and 4. counters before. Maybe these counters have some hardware failure. How can I fix the failure if any? Very thanks...