I have setup a sensor with 4 channels, 2 of which should show an error if offline. The other 2 should not be an error if they are offline. I am using prtg.standardlookups.connectionstate.stateonlineok and prtg.standardlookups.connectionstate.bothok.
The guage for prtg.standardlookups.connectionstate.stateonlineok points to the right for a value of 1 (and left for a value of 0).
The guage for prtg.standardlookups.connectionstate.bothok points to the left for a value of 1.