communication with micrologix 1200


Thread Starter

Eng. Antwan Naseem

I have plant running with PLC Allen Bradley Micrologix 1200 and i can't connect it with programming cable. when i try this cable in another plant connect without any problem. but i don't know why didn't connect in this PLC. Is this PLC is being protected? and i use RSlinx 2.57

bob peterson

It could be several things.

The most likely thing is that your communication settings in RSLinx don't match what the PLC is set to. Could be something as simple as baud rate. Did you try autoconfig in the DF1 driver?

It might also be that the PLC is set to DH485. You would need to use a DH485 driver to access the PLC if that is the case.

The serial port might be configured for another protocol; DH485, DF1 Half Duplex, ASCII, Modbus, etc.

You can set the Channel 0 serial port of a MicroLogix 1200 controller to default settings by pressing and holding the DCOMM button until the DCOMM LED comes on steady. The port will run at 19200 baud, 8/N/1 framing, DF1 Full Duplex.

If you press and hold the DCOMM button again until the LED turns off, it will revert to whatever configuration it is programmed to use.

Antwan Naseem

> Is you PLC is connect with other device?
> which port Are you using to connect with PLC?
> May be your port of PLC set for modbus.

yes this PLC connected with Panel view 550 from communication port (CH 0) and i removed HMI cable and connect programmable cable but i can't connect.

and i try also to connect HMI (PanelView 550) but the same problem found

Bob Peterson

what protocol is the PV using? DF1 or DH485? You would need to set your RSLinx to the same protocol.

antwan Naseem

> what protocol is the PV using? DF1 or DH485? You would need to set your RSLinx to the same protocol.

I think DF1 PV contain one port only Serial

antwan Naseem

> Just because it is an RS232 port does not mean it cannot be DH485 protocol.

Sorry I want to know how i can define the connection of DH485 on RSlinx and i will try
if i want to change the default configuration for coummincation and set my own can u tell how i can???

and Lets suppose there is some configuration set to communicate b/w HMI (panel view) and Micrologix 1200, i dont know abt these settings i make it default by DCOMM button download my new program through RSLogix 500 and again toggle the setting with the same DCOMM button. Will the setting revert and the processor will communicate to the same HMI ?

your reply will be appreciated.. :)