I've gone a step further in my monitoring on the Dude. I test for a communications fail, and if it fails, I return a value of -1. Then I have a function the alarm probe uses, that during a communications fail will return a value of 24 if the alarm is already clear, and a value of 0 if it's in alarm. That keeps the alarm from bouncing if there is packet loss, and also keeps from telling you the Power Supply has failed, when in fact you've lost communications to the site, which is better reported by a single dedicated probe. With simpler probes, a communications failure will return a value of 0.
Because of what I do to avoid the alarm bounce on communications failure, by faking a value, I normally use separate probes for alarms and charts, in our case I don't actually chart the PSU voltages. For your case, you'd want to chart the PSU1_Get_ROS and PSU2_Get_ROS functions. Then during communications failure, you'd chart a value of -1, which would make it clear what happened.
PSU 2 uses the same code as PSU 1, but with the appropriate references to the other OID and functions.
PSU1_Get_ROS (Function Code: returns voltage, or -1 on comms fail)
if(string_size(oid_raw("1.3.6.1.4.1.14988.1.1.3.100.1.3.7201",5,5)),oid_raw("1.3.6.1.4.1.14988.1.1.3.100.1.3.7201",5,5)/10,-1)
PSU1_ROS (Function Code: For the probe, returns voltage, or on comms fail +24 if probe clear, 0 if probe down)
if(PSU1_Get_ROS()<0,if(string_find(device_property("ServicesDown"),"PSU1 Alarm ROS")=4294967295,24,0),PSU1_Get_ROS())
PSU_Display_ROS (Function Code: For use on the device display, displays voltage, or "----" if comms fail)
concatenate(if(PSU1_Get_ROS()=-1,"----",concatenate(PSU1_Get_ROS(),"vdc"))," / ",if(PSU2_Get_ROS()=-1,"----",concatenate(PSU2_Get_ROS(),"vdc")))
(Device appearance: Just the voltage function shown)
[PSU_Display_ROS()]
You do not have the required permissions to view the files attached to this post.