I have to install remote "cycle start" and "cycle stop" for a Sinumerik 840DI, using PLC Inputs.
With the help of Siemens manuals, I found the keyboard keys are mapped to Input Bytes 0 to 7. In my case cycle stop = I2.0 and I2.1 for cycle start. Those bits change to on and off when pressing corresponding button.
My idea was to add new input in plc program to start and stop cycle.
I'm surprise to see that input I2.1 is not used in the plc program.

Someone have an idea to start a cycle from the PLC ?
Thanks for help,
Guy