2 Micrologix 1000's Broken, any ideas?

Hello all, I have a question. I have 2 micrologix 1000, both of which are just giving me fits.

#1 Will let me communicate and program, and test for a few minutes, then the Fault light will come on, and nothing will happen. I can not communicate, and it will not respond to any inputs. If I leave it unplugged over night, it will work again the next day for a few minutes.

#2 Will let me communicate and program it. The Input LEDs will respond to switches, however it will not react to those inputs? When connected to rslogix, if I close a switch, the LED will light on the controller, but the input on the rung will not turn green. As far as the outputs, if I Force an output, the Force LED will come on the controller, but the output relays will not click, nor will the output LED light.

I seem to be stuck, any ideas?

Thank you!

#1 Check with your AB distributor - IIRC there was a batch of MLs that was recalled for comm problems. Your distributor can check if you provide the serial number.

#2 Is the PLC in run mode?

#1 Will let me communicate and program, and test for a few minutes, then the Fault light will come on, and nothing will happen. I can not communicate, and it will not respond to any inputs.

Click to expand...

If it goes into Fault Mode, you cannot do any of those things until you Reset the Fault (the Fault LED goes off).

#2...When connected to rslogix, if I close a switch, the LED will light on the controller, but the input on the rung will not turn green. As far as the outputs, if I Force an output, the Force LED will come on the controller, but the output relays will not click, nor will the output LED light.

Click to expand...

You must Verify the rungs, then Download the program to the Micrologix, before it will control the Outputs. Just because you see something on your computer screen does not mean the PLC is also RUNning the same program.

My guess is that,
#1 You are overloading the internal power supply from the ML1000.
Never use the 24 volts DC from the ML1000 to drive anything but its own Inputs.
Driving anything more than its own inputs will cause overloads and the switch mode power will shut down and could eventually lead to blowing the internal fuse inside the ML1000 (yes there is one and it is not obvious).
Now this brings me to #2 was it doing service where #1 is now and already has blown the fuse.

Like I said My guess.

Got one of them working!!
Thank you guys! I thought about the power supply comment, I had hooked a small warble buzzer to the 24 volt supply, and didn't think anything about it. Very small ma usage. Anyway, I took both of them apart, and switched the power supplies around.

So, at this point, I have a fully functional #1 main board with #2's power supply. I have it cycling a simple program, running for over an hour now with no problems.

If the other powersupply blown the fuse controlling the output lines, where might that fuse be? Itafter figuring out all the little tabs, I finally got the little power supply board out......Hmmm just as I am typing this to you, I now see a little circle item marked "FUSE", never seen a fuse like that before. Well, I guess I'll test it on the meter and see if its any good.

Checked Fuse, it appears good, but I just tested it incircuit, didn't unsolder it. From what I can tell, this fuse is the main 110v line that feeds the transformer, so I assume it is good, because the board lights up. More tinkering tomorrow.