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Setting a sensor or channel to down state when below maximum



I have several SNMP OIDs that monitor a number of connected devices. These devices are managed, not client devices and therefore a static number.

I made a sensor factory that kept track of the number of missing devices, but because sensor factories cannot be saved in templates, it is not optimal.

I am looking for a solution that keeps track of the maximum value of a sensor or channel with static values. As soon as the sensor or channel drops below the maximum, the sensor or channel goes into a down or error state. This way I can hopefully save the sensor in a template and apply it to other devices.

maximum sensor state

Created on Mar 19, 2018 10:09:40 AM

3 Replies



Hello there,

Maybe I'm overlooking something here (for example why you've used the sensor factory for this in the first place), but you could set such limits directly in each sensor's channel (click on the channel to open its settings and enable limits there).

Kind regards,


Created on Mar 19, 2018 2:25:26 PM by  Erhard Mikulik [Paessler Support]



Hello Erhard,

I think my question was not clear enough.

I have a controller for access points that uses 2 values for monitoring the connected access points. 1 measures the number of expected or configured devices (something like 30 devices configured in total) and the other measures the actual number of connected devices (ranging from 0 to 30, with 30 being the maximum).

Because this can be different on every controller, just setting a limit will not work well as every controller has a different number of expected or configured devices. This means that the maximum number of connected devices is different per controller. This would have been solved if there was an OID available that kept track of the number of disconnected or missing devices. Something like this exists, but this is a table that only has entries when a device is missing or disconnected.

PRTG cannot read tables that are empty, so I made a sensor factory to subtract the number of actually connected devices from the total number of expected devices. This was working as I had intended, but the sensor factory cannot be saved to a template.

This is why I am looking to set a channel to down if it falls just below its maximum. It has to be dynamic and not just a static number.

Created on Mar 19, 2018 2:55:16 PM



Thank you for the additional details. In the end, the factory sensor is still the best option. What you can do would be cloning an existing factory sensor and then update its details in order to pull the data from the required sensors.

Templates are out of the equation, wouldn't make sense anyway, since the factory sensor is being configured completely individually and manually to pull data from certain sensor channel(s). So if it would be able to end up in a template, it won't be much more than a clone of the existing factory sensor, because how should a factory sensor in the template magically guess which channels from which sensors it should access then? :)

Kind regards,


Created on Mar 20, 2018 9:31:04 AM by  Erhard Mikulik [Paessler Support]

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