Serial port hijack - rfx Domoticz & rfxcmd

[AdeptusDomesticus]

Background
I have Domoticz with rfx433 enabled, which receives input from a number of sensors, and I use rfxcmd.py to transmit a raw string to a set of devices which require a custom signal.

All fine, except when rfxcmd sends a signal it hijacks the ttyusb0 from the Domoticz rfx, causing a serial port closed, end of file. This requires a machine reboot to overcome.

The question
Is there a way to send a custom string to rfx433 from within Domoticz ie not using rfxcmd.py?

Any other workarounds would be greatly appreciated as I’m running out of options other than getting another rfx433 unit and running it on another usb Socket, which may itself have some problems.

Things I have tried:
Reverting back from latest beta to stable
Setting a persistent path for rfx

System
System: Debian stretch / atom processor / rfx433
Domoticz version: 3.5876

Thanks in advanced