Onkyo Binding combined with node-red

I have just installed the Onkyo binding and interfaced to my TX-NR515. I am now monitoring the state with a Node-Red Home-Automation state node that is connected to OpenHab. I can easily detect changes in the input selection, but what I can not appear to do is detect a state change when I power the receiver off with the remote - regardless of whether I am looking at the OpenHab gui or Node-red. My working assumption is that powering off via the remote is actually putting the receiver into standby mode and so a ‘power off’ state change is not being detected - will test this later. Has anyone encountered this before and figured out how to detect a power off.