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Compare values with previous reading and divide by time.



Hi, I'm sorry that I'm quite new to the prtg and learning how to use it, I hope my question not a silly one...

I have a device use custom OID which contains an accumulative value(Volume of network traffic in bytes for every 30 seconds), the device OID is not standard and it don't have a uptime oid, therefore the delta (counter) option is not possible to use with that device.

The action I trying to do is "take the current value from the OID(e.g.", subtract the last value of the sensor channel receive from same OID, and divide by 30 seconds. and finally display the calculated result. and also discarding the calculated result if it is lower than "0".

The calculation is: (Current OID value(save it in a "Gauge(signed integer)") - (Last OID value) / (30 seconds)

Is there a way or any option to make the prtg "read the sensor channel last value? do the calculation and then display the result in the PRTG chart, and also copy an OID value into same sensor but different channel and save it for future use?

calculation last-sensor-value no-uptime-oid

Created on Jan 12, 2018 3:50:53 PM

1 Reply




Thank you for the KB-Post. I'm very much afraid this scenario is not possible for built-in sensors in PRTG. Sensors directly themselves on know their current value (named "Last Value" in our nomenclature, I apologize for the possible confusion), but do not have the previous value at hand.
The same applies for the Factory Sensor. It's only able to access the current value of any source sensors.
I'm afraid to solve this, you'll need a script, which uses net-snmp or similar to gather the actual raw value from the target, stores it in a file, performs the delta calculation and also division, and then returns the delta-value to PRTG.

best regards

Created on Jan 15, 2018 11:29:20 AM by  Torsten Lindner [Paessler Support]

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