Encoder question: complementary encoder output wired to a single-ended input

I have an incremental encoder with line driver complementary outputs. I would like to wire it to the built-in high speed input on a Micrologix 1200, but this is not a differential input, just a single-ended 24V input referenced to 0V. Can I connect this encoder, or do I need to order one without complementary outputs? If I hook it up, do I need to tie the /A signal to 0V, or do I just leave /A hanging?

Thanks in advance for any ideas you have.

First of all it depends if the encoder output is a RS-485 line driver or if it is one of the HTL drivers. I don't think the ML1200 inputs will take a 5VDC signal.

Assuming that the encoder is an HTL output model and the encoder and the ML1200 use the same supply and common you should be able to drive the ML1200 input with the A output only. You lose the noise immunity and transmission benefits of a differential line driver, though. Don't connect /A to anything. The way many of these drivers work A and /A will be alternating between supply and common. Connecting either to common can be a bad thing.

Keith

Thanks for the info. The encoder I'm looking at is a BEI H20 encoder with a 7272 Output IC, which is supposed to give me 24VDC out if I provide it with 24VDC in.

I also have an encoder with 5VDC output, but you are correct that it will not work with Micrologix inputs.

We have a BEI H25 with complementary open collector (7406) outputs and supply of 15VDC. With a 470 ohm pullup channel A drives a SLC fast sinking input card all day long with no problems. NOT A remains unconnected.