How To FLUSH out enet channel on 5/05

Does anyone know how I can flush the communications for the
ethernet channel on a SLC 5/05 on first scan of the program?

The reason is as follows:
I have two identical processors, powered all the time.
One is connected to the ethernet, and in RUN, the other is not, and is in PROG.
At a time to be determined, the processors are both placed in PROG, the ethernet cable is moved, and then the one with the cable is placed into RUN. When this happens, the communications do not restore.

The ethernet cable is attached to a switch, and the only communications to it are from a PanelView Plus 1250. If power is cycled to the panelview or the SLC, the communications are normal.

So, the question remains:
Can any software be written to 'initialize' or flush the channel?

Before I go speculating, try three simple tests:

1. During changeover, cycle power to the Ethernet switch only.

2. Run another Cat5 cable from the switch to the second SLC-5/05. During switchover, don't move the cable from SLC #1, rather just unplug #1 and plug in #2.

3. Leave the system with communications not working and wait. If this has to do with the ARP cache in the PanelView Plus operating system, the timeout should expire in a few minutes. Try giving it a half hour, as I've seen some timeouts set that high.

I'm betting that Ken is correct with #1 and #2.

Ethernet SWITCHES, unlike hubs, essentially determine the MAC address of a device connected to a port during initialization. The MAC address is associated with the IP address of the device. You can freely change IP's of the device, and the switch will re-create it's internal routing tables, but changing the MAC number attached to the port will cause a problem.

When you connect a different CPU to the same port of the switch, it is basically ignored, as the MAC number is not what is expected at that port. Re-initializing the switch, will rebuild it's internal IP/MAC/Port tables.

The above is because of the inherent nature of switches; they try to create point to point connections between ports, and not just blindly echo all traffic on all ports (as hubs do).

not so

Well, the panelview is part of the problem, for sure, but not
THE problem.

If I disconnect the front port wire, and move it to the other
processor, even the programming terminal cannot find it via
RSLinx.

If I disconnect from processor A, power down the panelview, and connect to processor B ... THEN RSLinx finds the processor.

Disable the port via external switch, or input bit, set the switch to off to disable the port. When the cable has been transferred to the new process then enable that new port via another external switch. (a three position switch, maintained position is a good choice) When the first port is disabled, it is timed out by the ethernet switch, when you remove the cable and insert it into the other dead port, the ethernet switch will not see it as an intrusion. Then after the cable is transferred flip the switch, which enables the new port, and the newly active ethernet connection will get assigned.
The panelview will not follow unless each PLC port has the same address, then the panelview would just see it as a loss of comms, re-established, the ethernet switch would have already done it's MAC thing so it should work.

Just a bitmore....

PS. You may also have to send a reset bit to the PLC ethernet port.

how do I 'send a reset bit' to the ethernet port?

Do you know the word number and bit number offset in the status file?

I have set the inactivity timer to 1 minute. The help file says
that the port will reset after up to 2 minutes (not a problem in
this app.)