Serco's Module 1756-M16SE All 3 LED's Steady Red. Any thoughts.

Good Evening ,

I have a urgent problem that I never seen happen before. I have 2 identical machines . One faulted out , with the 1756-M16SE Serco's module showing all 3 LED's Steady Red. All the modules such as 1756-IB32 , 1756-OB32 , 1756-IB16 , 1756-OB16 , 1756-OF8 , 1756-OF8 and 1756-IR6I all faulted out.

I go into RS Linx and I'm missing the 1756-L62 CPU , 1756-M16SE , 1756-OB16 and 1756-OB16 . Thinking I have a Backplane issue , I replaced the backplane but the modules still fault out .

I can't reload the program , because I cannot go online with the processor.
What serial cable can you use with a 1756-L62 , and USB for the laptop end ?

Really confused . Rockwell is confused also.

Thanks so much for your help.

Remove everything from the backplane but the Ethernet module (presuming you have one).

See if you can browse in RSLinx and see the size of the backplane; that suggests the backplane is OK.

Then start plugging the modules back in, one at a time. Since it's the 1756 system, you can do it hot, or switch off every time.

My expectation is that it's the SERCOS module interfering with the backplane, since it's the most complex thing you described.

What are the LEDs on the CPU showing, particularly the RUN and OK LEDs ?

Most general purpose USB/RS232 cables will work with ControlLogix (and a null-modem cable). I strongly prefer the Keyspan/TrippLite USA-19HS, and know that it works with "auto config" in the DF1 Full Duplex driver.

Thanks Ken ,

CPU looks good. Run LED on solid , I/O flashing because of the I/O faulted .
OK is on . I have a CP3 ( serial to USB ) cable would that work ? I can't find the Com port on this Windows 7 . About the backplane I did replace that . I would love to reload the program but I can't access the CPU .

Do you have an Ethernet module ?

If not, then plug only the CPU into the backplane, and connect using your USB/RS232 converter.

You will need a driver from the manufacturer, if the device doesn't enumerate as a COM port on your Windows computer.

Yes , I have a 1756-ENBT module . I would feel better if I could get into the CPU . Thanks

It sounds to me like something is interfering with the backplane communications.

Since you have replaced the backplane, it's probably not the backplane chip itself, so it has to be one of the chips (or the power supply) that interfaces with it.

Install one thing at a time and verify that they work. ENBT, CPU, I/O... then SERCOS last.