Is it safe to connect the COM on a VFD to gnd?

I've just realised I've never needed to worry about this before, but it's the first time I'm needing to connect a VFD to a 0 to +/-10V output that isn't isolated.
The inverter in question is an old KEB Combivert, and I can see nothing in the manual warning against not connecting the COM to gnd. Having scanned the manual for the Huayang inverter, it makes no mention either.

I'm just wanting to clarify before I blow the inverter and/or KFlop/Kanalog!