Bit To Trigger Cylce Power

tkareus

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Join Date
Oct 2012
Location
Indiana
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Is there a bit on the SLC5/05 processor I can one shot to trigger cycling power on the processor?

I know I shouldn't have to but my Ethernet connection keeps dropping out every day or two even though the processor keeps running.
I simply reset the power and it fixes it. Figured I could just trigger a reset at 3 AM if their is an internal bit that could accomplish this.

I've tried another processor and I get the same result. I've changed Ethernet cords and ports on the Ethernet switch and still no luck.
Only effects the processor. All the other Banner and Red Lion products on the Ethernet switch work fine.

Thank you,
Tom K.
 
The only thing I can think of is have the PLC turn on a relay that interrupts the 120 power to the rack through a N.C. contact. When the PLC shuts down the power will come back on and restart the PLC.

If you want a longer off time have the PLC trigger a timer that shuts off for a few seconds.
 
There is something else going on (most likely), that you are treating by cycling power.

I would not trigger a PLC to shut itself down automatically, make a human being perform that action until you get to the bottom of the root cause.

Look at the number of connections being used vs. available on the channel status page, check for messages that are in error, analyze the network it utilizes including switches and their settings.
 
Is there no way to reset the Ethernet port without cycling power?
One way to do the power cycle would be to wire a relay to a PLC output and wire the PLC power across a normally closed contact of that relay. Add logic to the PLC to turn on the output between 3:00:00 and 3:00:01. Turning on the output which will energize the relay which will cut power to the PLC. As soon as the PLC stops, the output will de-energize, restoring power to the PLC. Turning the output on between those two times should ensure that the relay doesn't get re-energized upon power restoration since it should take more that one second to go through a reboot. Can you be sure that the PLC won't be controlling something at 3AM that should not be interrupted?
 
tkareus,

you are NOT allowed to do what you are proposing !
the powers that be will have a field day when they find this out.

this violates a number of safety rules.
you cannot automatically remove power from a plc and then restart it.
what if someone was in the machine when it restarted and got injured?
the plc timer could be off and shut off the power during production.
what if an added shift was in production and the system reset?

see nfpa 79, I cannot point out the specifics.

so many things can go wrong.

james
 
I'd be pointing the finger at the switch. Is the link indication on the PLC and/or switch on when you lose the port? Just because you are losing comms to the PLC doesn't mean its the PLC that has the problem.
 
While I stand by my original statement, I see that you've already replaced the processor. My apologies for not noticing it earlier.

Based on reading your entire post, I agree the switch should be your next target.

In the meantime, be sure that the switch is grounded. I've seen instances where a poor ground actually interfered with its operation.
 
The next time you have to cycle power - cycle the switch not the PLC


If that also restores comm's then take the advice given and replace the switch.
 

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