1756-l55 ok red indication

[sandy5020]

Hi,

I just bought a new control logix 1756-L55 from a supplier in UK. The Red indication is showing stable and as per the manual its showing CPU not responding or faulty so I requested supplier to replace it and they send a new one and that one also same situation. Is there anything to do from our side prior to starting the CPU?...or is it a chasis issue

Regards
Sandy

 

[JTCat]

Hi,
Does this model have the memory card slot?
The L55 requires a memory card. I think there's a publication on it.

 

[JTCat]

Yes, there is. 1756-IN101

This will help you solve this issue.

 

[Contr_Conn]

If processor has only one label for L55 and no second label for the memory then most likely this is the issue and you will need to buy a memory module.
Also I would really question “new” as this processor was discontinued 15+ years ago,
Therefore you may not be able to find a “new” memory module for it.

And ignore USB advise above - this processor never had an USB, but there is a serial port on it.

 

[AlfredoQuintero]

And ignore USB advise above - this processor never had an USB, but there is a serial port on it.

Ooops! Sorry about that and thanks for clarifying.
Edit: I was able to delete the post, fortunately.

 

[joseph_e2]

As mentioned above, the L55 will not work without a memory module installed. Normally, we would order "1756-L55M12", which includes the memory module. To get just the CPU, get 1756-L55. For just the memory module, get 1756-M12. That's one size memory module, there are others. Here's an installation guide that covers the memory module:
https://literature.rockwellautomation.com/idc/groups/literature/documents/in/1756-in101_-en-p.pdf


The highest firmware supported by the -L55 is v16. It's been obsolete for a very long time. What's the reason for using this processor?

 

[pesedo77]

1756-A4 is the chassis itself, and does not include the power supply or the CPU.

If you can download and install an older RSLogix 5000 version, you can do testing and learning with much older controllers, which are very cheap on the aftermarket. 1756-L1 support up to v13, 1756-L55 supports up to v16, and 1756-L6x support up to v20.

If you're buying a new controller and want to use v30 and v32, then buy a CompactLogix, even the very small 1769-L16ER.

 

[Operaghost]

Are you able to clear the fault?

Try turning the key to PROG, then RUN, then PROG again. Don't stop at REM. You have to go all the way to the right, then all the way to the left, then all the way back to the right again to clear a fault.

See if that clears it.

OG