Powerflex 525. Ethernet loss

Hello.

Got two powerflex 525 set up. I was using digins to control drive although it was connected to a network. I didn't have any faults coming up saying it had lost comms. As soon as I started giving commands through Ethernet/ip every so often both would drop off the network for a small period of time then re connect. This put a fault onto the drive though which is causing problems. The Ethernet cables are fine. Also the network is fine as I can go online with the plc through a different switch from the drives and I never lose comms.

What is the exact fault code being indicated by the drive ?

In general, unless the drive is using the I/O connection for control, it doesn't care if that connection is faulted or not.

How do you know that the cables and switches are good ? What sort of diagnostic and monitoring equipment are you using ?

If the problem is between the switch and the drives, then it makes sense that a connection from a different network location to the controller wouldn't be affected. While comms to a PLC from an engineering workstation suggest that the network isn't badly degraded, they don't prove that it can handle cyclic I/O.

Your other posts suggest that you've got a device-level ring system. Are you also using some other switches connected to the DLR network ?

Do the drives only drop the comms after you start them, or while the motors are running?

Are you using N-Tron switches?

After you start them. They have cut out whilst the motors are running as well.

CallumMacEwen said:

After you start them. They have cut out whilst the motors are running as well.

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Check your cables and all your earthing on the motor supply and Ethernet. I suspect you're dropping comms due to interference. This will only happen once the drives are outputting. Are you using CAT6 STP? Are the network cables run with the motor cables? Ping the drives while they are running, and while they are not, and see if there's a large difference in response time and packet loss. If you are using a managed switch, you can also check the switch logs and stats on those ports or IP addresses.

As a quick test, pull the network cables out of the trunking, and just run them point to point across the panel. If your problem goes away, you know what needs to be done.

I think the earthing is suspect as it was an old installation. The network cables are run close to the motor cables inside the panel but not the entire run. No it's not cat 6. It's cat5.

CallumMacEwen said:

I think the earthing is suspect as it was an old installation. The network cables are run close to the motor cables inside the panel but not the entire run. No it's not cat 6. It's cat5.

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CAT5 will be ok, as long as it's STP of SFTP, and the shielding is actually connected. If you're running unshielded for any reason (CAT5 UTP, failed plug shield connection or failed port shield connection), you're leaving yourself wide open to noise.

A subtle example were 2 servo drives with CAN/ProfiBus in one of my panels. They had over-stripped the motor and CAN cables, leaving the whole lot free to act as antennas. In that case, CAN was dropping on comms timeout.

The run from the main switch to the switch inside the panel is run in cat5 unshielded. See if i use shielded cat5 from the switch in the panel
To the two drives do you think that would work or should I replace the main unshielded cat5.

Running STP inside your panel is a good start, and should only set you back a few dollars. What sort of run are we talking between panels? Is the Cat5 running through the plant, or other machines? How long is that run?

I am on site now and I have replaced the two cables from the drive to the switch. It's early days but it hasn't cut out yet. The run is 20M but it's going above a suspended ceiling.

CallumMacEwen said:

I am on site now and I have replaced the two cables from the drive to the switch. It's early days but it hasn't cut out yet. The run is 20M but it's going above a suspended ceiling.

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Replace that one too. If you are a person, or have people who can terminate STP properly it will help, otherwise buy pre-fabricated. For panel cables <10m we use pre-fabricated, but will use STP off the roll and something like a Panduit ISPS688FA to terminate. Also for long runs outside the panels.



I was working on a water filtration project a few years ago. The contractors had run Cat5e from one control container to another, about 50m across the plant. Every time we fired up a 40kW recirc. pump on a VFD, the comms between our container and the GE Water guys would drop out. I had a fail-safe in place at the time for a super-heated steam supply, so the whole lot would shut off and purge the system when it happened. Long story short; the installation is only as good as your weakest part.