my last question of this thread product confusion is still not answerd.
"Is TER GX 300 fully compatible to TER GX 110?"
No, it is not.
GPIO 3 (input at power connector) mutated to a relais contact and the IOs 4,5,6 and 7, with free configurable direction are now fixed to two inputs and two outputs. Further they've done something to the IO voltage, where it was some 3V there are now 12V at the RJ11 connector.
The TER GX 300 owns an USB port, I found neither any function at the module, nor any documentation on the TechDoc-Page. You surely have it connected, what does it do?
How long will be TER GX 110 available?
Do you have another replacement? It should provide GPIO 3 like mentioned above, three GPIO as input one as output. The serial port (RS232 level) is needed too.