AB 1756-ENBT stops

RSLinx doesn't care. Your Logix application might, if the connection to the module is keyed.

Since it's not in the I/O Configuration, that points more solidly to the issue being the module itself. The only reason the PLC would even care that it's in the rack is if it was using it to communicate with something else (IO or another processor),and it would need to be in the I/O Configuration for that to be happening. Since it's not in the configuration, the PLC won't care.



I guess it's possible the PLC could be using it with a MSG instruction with the path manually set. You can verify that by going to the tag window and sorting by datatype. Look for a "MESSAGE" tag and cross reference it. Look at the Path in the MSG instruction to see if it's going out through the module. I would be really surprised to find that the PLC is using the module without it being in the I/O Configuration.



If you want to add it to the I/O Configuration as a test, you can. Just set the electronic keying to compatible keying and the newer module won't be an issue. I really think you're going to find that the module itself is bad, though.

I checked Keying Mode. It is Compatible Keying.

I checked the program. There are no MESSAGE type tags in use.
And I added the ENBT module to I/O Configuration folder.


And after three hours the module stopped working again. It displayed "Exception 0300" message.


I am going to "steal" another ENBT module for swapping, if my boss allow me to do that thing.


And probably you will laugh at me, but the upper and lower plastic plates on the ENBT are very tight and I'm afraid to break them off by accident. I never took a 1756 module out from a 1756 rack before.

My question is: In what exact direction should the plates be pressed to take the module out from the rack? Should I push them toward the back plate?

You press the top one down and the bottom one up at the same time, you may need to gently move it from side to side or up and down to get it out of the rack.

I would like to thank you all for sharing your knowledge and time.


(For me It's better to ask before replacing, because I wouldn't want to end up with two modules with the same failure.)
Could the such failure of the ENBT be caused by a bad signal from the rack or by bad power feeding from the rack?

GreyVlad said:

I would like to thank you all for sharing your knowledge and time.


(For me It's better to ask before replacing, because I wouldn't want to end up with two modules with the same failure.)
Could the such failure of the ENBT be caused by a bad signal from the rack or by bad power feeding from the rack?

Click to expand...

It's possible, but not super likely in my experience. To test that, you can move it to another empty slot in the same rack (if any are available). If it still fails, move it to another rack altogether.