Using ethernet extenders for ControlLogix to ethernet FlexIO

Greeting to all,

I have "inherited" a ControlLogix PLC with an Ethernet card (1756-ENBT) in Building 1. There are three ethernet FlexIO racks that are being controlled 6,000 feet away in Building 2. Using fiber is not an option. There are two 25-pair aerial cables that connect the two buildings. Currently there are Patton ethernet extenders that connect the devices but every so often (once a day) communications is lost for a couple of seconds.

I am looking for a recommendation for ethernet extenders that is meant for continuous industrial controls using copper twisted pair. I did some searching but all recommendations were for fiber optic cable.

Thanks in advance,

Mike

Have you contacted tech support about this issue? I ask because I have never seen this and I have some 2150's running over twisted pair about 2600 ft apart. never had a single issue with comms loss.

IMO that is a good brand of hardware you have for this application. What model are you using?

I am using model 3241 and they are running at 1024 kbps. I have tried using other comm line pairs but the comms loss still happens.

The ethernet FlexIO is controlling 7 analog outputs which are used for a speed reference to 7 DC motor drives. The analog outputs are setup so that if comms is lost to the FLexIO the analog output goes to 0.0 volts and that stops all the motors.

My recommendation was going to be Patton... so I won't be too helpful there.

I'm curious about the mechanism of failure; is there a constant level of packet loss that occasionally goes above the four-in-a-row threshold, or does it tick along perfectly until some external interruption causes a total loss of communications ?

Take a look at the I/O Connection list in the 1756-ENBT's embedded web page and check the "Lost" counter for each I/O connection.

The "Lost" counter increments when a cyclic Input data packet doesn't arrive at the expected time, but another Input data packet arrives before the connection times out. If four expected packets in a row don't show up, the controller declares the connection failed.

I'm also curious about what the Media Counters for the 1756-ENBT show. Since the Ethernet between the module and the repeater is likely pristine, I'm not sure what effect line noise or corruption will have on the Ethernet Media Counters.

Screenshots are OK (use PNG format; it's smaller than BMP and clearer than JPG) but the best way to grab diagnostic data from a web page is to use a "crawler" like WGET or HTTrack.

Thanks for giving me some ideas of what to look for. I'll report back when I find something.

Mike,

I will throw our hat in the ring.

We distribute Westermo. Below is a link to their Ethernet Extender products:

http://www.eternity-sales.com/westermo/wolverine_shdsl_ethernet.htm

If you have any questions, feel free to email or call.

Hope this helps.

Shalom and God Bless,