Communication errors

[bucks7756 0]

We currently have a panelview 550 hooked up to an IMC S Class motion controller on DH-485. We are trying to add a micrologix 1200 plc to the network through DH-485. The panelview is hooked up to one of the DH-485 ports on the IMC S Class and the micrologix will be hooked to the other DH-485 port of the IMC S Class. As soon as I hook up the micrologix plc I get an error message on the panelview saying "Data Errors on the link." Baud rate for all nodes is 19200. Panelview is node 1, IMC is node 0, and micrologix 1200 is node 2. Anyone have any ideas.

[Wordman 0]

Not familiar with that motion controller but isn't the 2nd port for a seperate connection? You are saying it is somehow the same network? I don't know how you have it laid out, but make sure you have 120 Ohm line impedance terminations at both ends of the line

[Gerry 13]

I think once you have 3 or more nodes, each node needs to have a link coupler (AIC, AIC+).

[gravitar 3]

I would have to agree with the previous responses.. The problem must be in the wiring/grounding/termination. Not in the mere fact that this additional node was connected. I think you COULD connect three or more nodes without an AIC.. But you sure would be putting yourself at risk of comms errors like the one described here! How many feet of cable are between the nodes? Are they routed away from any likely sources of interference? Is the correct cabling being used? (Belden 9842, if memory serves) terminated at both ends and grounded at one?

[bucks7756 0]

The panelview goes into a link coupler which is attached to one of the IMC DH-485 ports. The micrologix 1200 goes through a net-aic which is connected to the other IMC DH-485 port.

[gravitar 3]

The problem with network cabling issues is there's just so many things to consider.. Too numerous to mention. You pretty much have to have a set of trained eyes SEE how you have it set up, once the obvious problems (as mentioned above) have been eliminated.