Will the Allen Bradley Micrologix 1200 PLC Support 5 VDC Encoder Inputs?

[Craig Chamberlin 1]

Hello everyone, The reason this question comes up is because my catalog claims it will only support 12 to 24 volts... but it says the same about the Micrologix 1000 and I have had success with it reading it before. Has anyone actually been able to work with a 5 V input on the 1200 with success? Please advise.

[cooperg36 1]

I am not sure on your 1200, however, I have used 5 VDC on the high speed inputs to a ML1500 for years with no problems. Don't forget to configure your filter settings for the high speed inputs to allow them to read the frequency you desire.

[paulengr 44]

I'm not sure what you are looking at. In the selection guide, page 59, it says that "off state" is 0-5 volts, and "on state" is >14 volts for inputs 0-3, or >10 volts for the rest. That's the on board stuff. The input expansion modules have the same specs. This is one case where yes, the Micrologix line might not be appropriate.

[Bob A. 1]

Craig, In the past, I have used a transistor circuit know as an"emitter follower" to do level conversions such as you describe, usually for prox heads. The wisdom of this choise depends on your level of electronic skills and despiration. This would involve a few components and small piece of perf board to mount the parts. If you are at all curious, feel free to send me an e-mail at robert.applegate@comcast.net and I'll drum up an example. Best Regards, Bob A.

[TimWilborne 108]

I know it doesn't consistently work with the 1100 and the 1200. Where I previously worked our connectors were interchangable between the two. If someone accidentally grabbed the 5VDC style it wouldn't work. It was enough of a problem that we ended up changing the connector ends so that they couldn't be mistakenly swapped. It may be working, but I would say it's very marginal. Mine if I ask why you would want to?