One I've Never Seen

oldnerd · May 12, 2013

I have a A/B MicroLogix 1500 that exc. the prg just fine but can not communicate with it no matter what. Tried it with DCOM and everything I know. Changed cable no luck, the only thing I am not sure of is the USB to Serial adapter. Anyone have any ideas, be glad to listen.
Thanks
OLDNERD

jrwb4gbm · May 12, 2013

http://mobile.walmart.com/m/phoenix...igh-Speed-USB-Serial-Adapter-USA-19HS/5934005
This adapter works well with AB.

ATU · May 12, 2013

Is it password protected?

oldnerd · May 12, 2013

oldnerd · May 12, 2013

Thanks but adapter is working tried it on another plc.

jrwb4gbm · May 12, 2013

I'm guessing you already have the manual but if not here is a link. The comm info is in chapter 4. Maybe something in there will help. It's possible the comm port could be physically damaged also, especially since your USB adapter and cable works on another PLC. You didn't say this but is the plc you used in post #5 an identical AB MicroLogix 1500?
Link:
http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1764-um001_-en-p.pdf

oldnerd · May 12, 2013

Yes and thanks I got it, it was the USB to DB9 converter. I swapped to a UC232A and voila the coms was great. Don't know what happened to the A/B converter but I trashed it. Strange thing it worked once on another SLC but only once. Thanks to all for there replys.

Plastic · May 13, 2013

Dcomm

There is a "Default Comm" button hidden under the MicroLogix 1500 controller cover.

Press it until the "'DCOMM" light comes on, and your serial port will be back at the default DF1 Full Duplex, 19200 baud settings. Press it again until the DCOMM light turns off, and the port goes back to whatever System Mode or User Mode settings you have in the program.

brendan.buchan · May 13, 2013

Plastic said:
There is a "Default Comm" button hidden under the MicroLogix 1500 controller cover.

Press it until the "'DCOMM" light comes on, and your serial port will be back at the default DF1 Full Duplex, 19200 baud settings. Press it again until the DCOMM light turns off, and the port goes back to whatever System Mode or User Mode settings you have in the program.

No way! Never knew that's what the DCOMM light was for.

I'll have to go looking for that little button next time I see an ML1500.

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One I've Never Seen

oldnerd

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