Extreme newbie Micrologix 1200 questions

Hi everyone!

I am new to PLCs and need some help. I can brute force my way through the ladder logic, but the actual PLC installation & wiring has got me stumped. I have a Micrologix 1200 1762-L40BWA and RSLogix 500 Pro.

I'm building a new machine and doing some work on the bench with the PLC. It powers up and connects to the computer. I can force the outputs on and the output LEDs on the PLC light up, but no matter what outputs I turn on, I'm not getting voltage across any of the output terminals. I've looked at the AB output diagrams in the manual as well as the posts here, but it isn't clear how these should be wired. It looks a little like I need to jumper across some of the terminals to actually see voltage.

I would appreciate some advice, since I am reluctant to try too much with wiring for fear of frying the PLC.


Thanks,

Jeff

The PLC you're using has relay outputs; activating an output simply closes the corresponding set of relay contacts. You must provide your own voltage to one side of the relay (known as the "common") in order to see a voltage on the other side when the output is activated. So, for example, if you apply a voltage to VACDC0, then you'll see that voltage on OUT0 when the output bit is on in RSLogix. Relays provide versatility since you can run whatever voltage you want through the outputs (within the limits of the relay contacts of course).

Sometimes the relay commons are combined in a single connection. For example, VACDC3 is the common for outputs 4 through 7.

That is just what I needed. Thanks for the quick response!


Jeff