1794-VHSC Won't Count

[whirlair]

Is it possible that hooking the encoder to A- and B- could screw it up, that is how I have it hooked up. I did this because the open collector encoder is HI normally, and pulses to LOW (grounding the source). I also found that this was the only way to get counter mode to work so I figured it needed to be hooked up this way. When I change it to A and B (regular) I do not get any counts and the LEDs don't blink as expected.

So at the moment nothing is hooked upto A and B regular.

 

[kamenges]

Do you mean that the encoder output can establish both a high state and a low state on it's own without being connected to anything?

 

[whirlair]

Do you mean that the encoder output can establish both a high state and a low state on it's own without being connected to anything?

No, I don't think so. From what I understand open collector is basically TTL. So, if I have 5vdc going to the A- input and the A channel on the encoder there will be 5vdc at the input until the endcoder pulses, which will cause voltage at the input to drop to 0 and current to flow to ground.

 

[whirlair]

Well I actually got it to work! Even without a line driver encoder. So to close out this thread I'll put a few notes up for others. These are not in the documentation to my knowledge.

To do single ended open collector to 1794-VHSC you do NOT need a pull up resistor, apparently it has an internal one but the only way I know this is from watching the signal current with my meter (~5ma on, ~.5ma off).

Secondly you need to jumper 24v (or 5v) to the A, B, and Z inputs on the module. Then connect your encoder channels to the A-, B-, and Z-. Sounds simple but if you read the documentation you will probably end up the same way as me and waste tons of time trying to figure out why the hell the LEDs blink but there are no counts.

Thanks everyone.