ControlNet Redundant Media

[preacher.ca]

Good day,

I have contacted AnyBus support regarding this, BUT thought maybe someone here has suggestions as well.

Okay what I have. I have a vendor built system installed before my time which has sensors that monitor various points of a process. All of this is collected and self contained in their system. Great. Been like that for years. Now operations wants to integrate the vendor system with our control system (AB 1756-L63). Inquiring with the vendor, they already have a terminal strip setup with I/O points that can be used for this purpose. Looking it over I also notice they have an AnyBus ControlNet Serial Gateway which offers more signals without the additional wiring. This being the more favorable option, I set up the gateway on my test bench. Works good. I can send the gateway information from the PLC.

Now I connect the gateway to the field PLC. First thing is the ControlNet is setup with redundant media, which looking over the gateways specs, supports redundant media.

So I connect channel "A" and "B" to their respective taps and open RSLinx to see if it picks up. Nothing. Then I notice some of the nodes that were working now have a yellow triangle. I disconnect the gateway on both channels and those nodes returned back to normal. Trying again, same issue. Thinking maybe this has to do with scheduling, I setup this device in Logix5000, then open RSNetWorxs and scan the network. The device does not show. I import the .eds file and nothing.

Returning to the test bench I can install this device with ease. It picks up in RSNetworxs and RSLinxs no problem. The only thing the test bench does not have is the redundant media.

So anyone have any thoughts? Maybe there is something in the redundant media setup that I am missing? Something in RSNetworxs?

So far AnyBus has suggested to move the tap to another location and try again. I will have to wait for another down day to try this.

Any ways, thanks for your time. I will post the end result regardless.

 

[preacher.ca]

So far AnyBus has suggested to move the tap to another location and try again. I will have to wait for another down day to try this.

Yep... that fixed it.

All we did was insert a 3 meter cable in between the taps and magically this resolved the issue...

 

[Ken Roach]

Does the system have a very long trunkline or any sort of copper/copper or fiber/copper repeaters ?

ControlNet timing is generally very robust and capable of handling cable impedance differences, but if you have long cables or repeaters and RSNetworx hasn't been configured to account for them, you can push the edges of the timing envelope when you add just a little extra copper or another tap and node.

 

[preacher.ca]

Does the system have a very long trunkline

Unfortunately I do not have anything to measure the exact length, but I honestly can not see it being beyond 1000 meters, but then again, don't quote me.

any sort of copper/copper or fiber/copper repeaters

None.

you can push the edges of the timing envelope when you add just a little extra copper or another tap and node

Initially we installed the taps where three other taps were located, that way we wouldn't have to reroute the installed ControlNet cable. We knew the cabling and connectors were fine because all the previous devices still worked without error. As soon as I tried to connect the new device to the tap, things failed (Yes, I tried different taps).

So we made a 3 meter ControlNet extension cable and connected it to the original cable with a barrel connector and for some reason this worked.

Haha, I don't know what to tell you. Magic.