SLC500 2 RACKS over a distance?

[Bit_Bucket_07]

Good luck, these things are actually kind of a nightmare. I hope you have a TechConnect contract

Allen-Bradley's documentation for SLC Remote IO is probably the most poorly written and difficult to understand technical literature that they have ever produced. That said, once you figure it out and get it operational, it's fairly reliable. Even the analog IO is easier to deal with on newer SLCs that support BTR/BTW function blocks. It was always a nightmare having to write those "roll your own" block transfers in the older models.

 

[sparkie]

The SLC 5/05 (Ethernet) controllers do not have Ethernet Remote I/O control capabilities; you could explicitly (MSG) transfer data to/from Ethernet capable devices, however, the implicit Ethernet data transfer is available only for the Logix Class platform (ControlLogix, CompactLogix, FlexLogix, SoftLogix)

For the SLC controller family you could allocate remotely located IO via RIO (1747-SN), DeviceNet (1747-SDN) and ControlNet (1747-SCNR) only.

You are completely correct, but as I said it is tricky. You need to write heartbeats, handshakes and logic to handle connection losses, and it really depends on what the other racks are controlling (safety evaluation).

Now that you mention it though, depending on how his wiring is set up, a DeviceNet network may be quite a bit easier to set up and he could use the wiring he has in place. They both use RS485 if I'm not mistaken, but he would need terminating resistors at the ends of the loop.