Siemens latency

[thekman]

I am stuck trying to determine the latency of the I/O over a small network when incorporated into a program. I can determine the program cycle time, but do not know how to figure in the network polling rate as far as network input monitoring within the program.
I am using the new 0BA7 PLC with the ethernet capability, and Siemens is little or no help at all, as their tech support is as new to this thing as I am.

 

[stephenjvb]

Maybe I'm missing the point and I'm not familiar with these processors but you could simply toggle a bit in one processor, have a remote processor copy the bit to a second bit and time how long it takes the first processor to see the changed 2nd bit. If you toggled it 100 times (or more) and tracked the overall time you'd have more resolution or a good average time.

If your processors did nothing else you'd have the internet latency and the processor loop time combined, and you know the loop time. With lots of samples the PLC response time should average half the loop time for each PLC so the overall delay minus the loop time for one processor should be the network delay.

 

[IRstuff]

If you have sufficient ethernet resources, you can ping the remote IP address.

TTFN

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