AB CompactLogix L35E Stuck in RemoteRun

[Brad P 0]

I have a AB CompactLogix L35E. I can communicate with it remotely with my laptop. I can make program changes. I can switch from RUN to PROGRAM using my laptop. The L35E(PLC) display light never shows the OK light on. Also when switching the key switch from REM to RUN to PROGRAM nothing changes. It is like it is stuck in REMOTE RUN from the computer. In the computer software Ithe OK light is on. When I fault the fault it turns RED like it should. But only in the software. Any suggestions why this is happening? Thanks, Brad

[b_carlton 61]

Is this unit the only one? Is it possible, if you are on a network, that you are actually conneted to another unit?

[Brad P 0]

This is in our shop. It is the only one I am connected to. It works fine, But the OK light doesn't come on and the key switch doesn't switch between RUN,REM and PROG.

[Ken Roach 194]

It sounds like a damaged controller. The LEDs and the keyswitch probably use a similar set of pins or connectors inside. Check out the LED functions based on the chart in the Installation Instructions or the User Manual. The OK LED should only indicate the presence or absence or power, or the presence or absence of a major fault. It's the RUN LED that should change when you change from PROG to RUN. There's a rare set of circumstances where you can set stuck transitioning from RUN to PROG if you have a large number of MSG instructions queued but not complete. But that affects both a PC-commanded and keyswitch-commanded transition, and does not affect the Program -> Run mode transition.

[Brad P 0]

Thanks for your reply. The key switch will not take it out of run. I can take it out of run remotely using the software. I did a power supply change on this PLC. The power supply input voltage was set at 220V by default from Allen Bradley. I am using 120 volts. I applied voltage (120v) to the power supply that had the 220 volt dip switch set. One power up. Do you think this would cause this problem? Also we were installing a memory card when I noticed this problem. Thanks.

[Ken Roach 194]

Having the voltage selector in the wrong position will cause the processor to go into fault mode, but it should not damage the processor. Why were you replacing the power supply ?

[Brad P 0]

We had a power supply go bad on another PLC. I used my shop test bench PLC's power supply to make the repair. When the new power supply arrived on installed it on my shop PLC. The only other thing we were doing with the shop PLC, was we were doing a memory card program back up. I guess I will send it to our AB distributor and have AB look at it. Very strange. Thanks for your help.