DeviceNET in RSLogix500 MLX1500

[dburnum]

I got called today by our A-B supplier to see if I could help another customer of his. They have an MLX1500 PLC with a 1769-SDN module and apparently, the PLC has "lost its program". I'm unfamiliar with DeviceNET as we do not use it our facility, but I do have the RSNetwork for DeviceNET software for configuring it, but do not have the DeviceNET cable for connecting to it.
If the program were to be re-loaded to the PLC, does the DeviceNET configuration have to be reloaded as well? I would think it is just to set up nodes in the DeviceNET network.
Asking for a friend.

 

[Ken Roach]

The MicroLogix 1500 doesn't support "bridging" to the DeviceNet like CompactLogix does. To configure any of the devices on that network you would need a direct DeviceNet interface, like a 1770-KFD (serial), 1784-PCD (PCMCIA) or 1784-U2DN (USB).

But the DeviceNet scanlist is stored in nonvolatile memory inside the 1769-SDN module, so if that is undamaged and the only problem is in the MicroLogix 1500 CPU, then you won't have to touch the DeviceNet.

Ask the client to (or go and do it yourself) carefully observe the two-digit display on the 1769-SDN and report all of the numbers and the sequence in which they appear. If the only numbers are 80 and (a number between 0 and 63) then it's possible that the only problem is a MicroLogix program that isn't in RUN mode (including faulted or cleared).

80 = Scanner Idle. When a scanner is set for Node 00 (very common) and the CPU is in idle or PROG or has no program and the DNet is otherwise intact, you will see alternating "00" / "80" on the DeviceNet scanner. That's a good sign !

Most PLCs, of course, do not simply "lose the program", but of course you'll figure that out when you get onsite.

 

[dburnum]

But the DeviceNet scanlist is stored in nonvolatile memory inside the 1769-SDN module, so if that is undamaged and the only problem is in the MicroLogix 1500 CPU, then you won't have to touch the DeviceNet.

This is exactly what I was thinking. Thank you!