Micrologix 1200

[Simon Beswick 0]

I am trying to backup a program on a Micrologix 1200 PLC, without any success. I am using RSlogix 500 software and serial connection. I have configured the driver in RS lynx to DF1, but when I click on auto configure, it fails. Also I cannot see it when I browse.The plc is connected to an HMI , and I have noticed there is a button on the front, just below the comms port. Does anyone know what this button is for, its identified as comm. I have heard that when the button is pressed it toggles between default protocol and the protocol that the HMI requires. Can anyone confirm this.       

[IO_Rack 178]

For some reason we can't post images or links in the forums.

The manual you want is 1762-UM001H-EN-P. Chapter 4 outlines the communications in detail. You'll need to match your connection method with the protocol. Also, on some PLC models, the auto configure may not work. I don't remember which ones. I haven't used an ML1200 in quite some time.

[Joe E. 259]

After several attempts...

Are you using the cable that connects the PLC to the HMI? If so, try a null modem between the PLC and your PC, then autoconfigure. In fact, try the null modem adapter anyway.

Here's what the manual says about the COM button (page 4-3, pdf page 69):

Quote

Use the Communications toggle push button to change from the user-defined
communication configuration to the default communications mode and back
on Channel 0. The parameters of the Programmer/HMI Port are fixed at the
default communications configuration. The Default Communications
(DCOMM) LED operates to show when the controller is in the default
communications mode (settings shown on page 4-2).

Quote

The Communications toggle push button must be
pressed and held for one second to activate.
The Communications toggle push button only affects
the communication configuration of Channel 0.

 

 

 

Edited 27 Oct 2020 by Joe E.

[Joe E. 259]

14 minutes ago, IO_Rack said:

For some reason we can't post images or links in the forums.

...

Removing the link to the manual let me post something at least...

Try this:

https://literature <dot> rockwellautomation <dot> com/idc/groups/literature/documents/um/1762-um001_-en-p.pdf

Replace <dot> with actual periods...

[Simon Beswick 0]

I have the manual and have read chapter 4 previously. I just wanted clarification of what I think the button is for. Just to be clear if I press the button , then I should be able to communicate with the PLC, and then when I press it again it will then go back to the configuration of the HMI.    

[Joe E. 259]

That's what it looks like to me. I've never done it, though. I would try a null modem adapter first, though.

[Simon Beswick 0]

I have tried to communicate via USB to serial but to no avail. It looks like I am just going to have to bite the bullet and try it

[Joe E. 259]

Do you have a null modem adapter? Put that between your USB serial adapter and the PLC. Depending on what cable you use, you won't be able to connect to the PLC, even with default settings. If you're using the cable that the HMI uses, I'm 90% sure that you will need the null modem, no matter what.