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Old January 20th, 2023, 04:48 PM   #16
Dayvieboy
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I would imagine it might be possible to construct one with open sockets wouldn't it? Not that I would know how, but I thought Open Sockets opened all possibilities...[/QUOTE]

It is possible, but takes a bit of time and generally not something most PLC programmers have experience doing.

We have done communication via custom protocols in the PLC & via the SCADA.

There are so many protocols and most PLC's only speak a few out of the box. The SCADA has many built in.


Of course controls from hardware via SCADA to PLC are not Safety rated and only for general use.
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Old January 20th, 2023, 04:57 PM   #17
TheWaterboy
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Quote:
It is possible, but takes a bit of time and generally not something most PLC programmers have experience doing.
That is of course very true - a bit outside the normal scope.

I could see a value in RTU's that might have a handful of Ethernet connectable instruments but use a different subnet back through telemetry. It might be useful to have the PLC ping the local devices once in a while to make sure they are alive for when they are needed.
Granted there are often other ways to accomplish this with a heartbeat, but not always.
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Old January 20th, 2023, 11:25 PM   #18
Dayvieboy
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On most SCADA's
We ping every IP address on the PLC network
for troubleshooting.

Ping = ethernet is live
CPU usage = computer is booted up
Process name = software is up and running
Heartbeat = device is properly updating

Depending on it the device is a computer, flow meter, PLC
different combinations of this data pinpoint problems
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Old January 24th, 2023, 11:57 PM   #19
tlf30
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Ping is usually implemented with ICMP, and to my knowledge there is no way to trigger an ICMP ping from a CLx. However, there is such a thing as a UDP ping, which is more common on Unix based systems. You can create a UDP datagram with the Open Socket messages in CLx. You may be able to implement a UDP ping using those. However, it will be complicated and there are probably better options such as creating a CIP connection between the PLC and the computer using a CIP server. Many CIP server options exist in phython that can be used to build something simple like what you need.
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Old January 25th, 2023, 12:03 PM   #20
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One possibility is to run a small program in python to read a random or counter data tag , if the data from the plc does not change or it is impossible to read, that means that the comm between the pc and the plc has been interrupted.
The OP mentioned a compact logix so pylogix can come to the rescue, DMROEDER is in front of pylogix, you can contact him here.
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