PRTG has provided a value (-48dBm as signal level for our wireless link). This value appears under Message column. Is it possible to graph this value? How can I set a notification if this value goes up to -70dBm?
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As for #1, yes. This is possible, there are a couple of ways of doing so. Please refer to;
As for #2, As soon as the numerical value shows up in a Sensor Channel, you will be able to configure limits, alerts and everything else.
Before being able to "evaluate" the value (from this string) one needs to extract the numerical value, for instance with a regex expression.
For this situation (A positive or negative value with one decimal place), to extract the numerical value you require the following regex expression:
| (-?\d+\.\d+) |
The set-up (in the sensor's settings) will look like this: 
After this was configured, a new channel "Extracted Value" will come up in the sensor. When this happens, one can use the standard "limits" feature to get alert when the value goes above/below a specific threshold. This is how the limits setup would look like:
With this configuration, the sensor will go into Warning if the value goes below -55. For Notifications (as well as alerts) please add a new State Trigger for the corresponding state (Warning) to the sensor (in the Notifications tab).
Disclaimer:
The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.
