Hello,

yes it is possible. When using no PLC it is necessary to use DCC for the logic, and TB30 or TM31 for a analog input.

DCC

https://support.industry.siemens.com/cs/ww/en/view/109776202

For controllling the setpoint for torque limiting value, you need "Technology Controller" to compare actual torque with the torque setpoint.

9.1 Technology controller

https://support.industry.siemens.com/cs/ww/en/view/109781535

Yes, the simulator is basically a motor in regenerative mode.
You use speed control with small speed setpoint, e.g. 1.0 rev/min and set limiting value between 0 and x Nm.

To deactivate monitoring you have to set P1545 = True;


How accurately can I control the torque?

This depents on the resolution of the external torque sensor.

If the torque setpoint is set to zero, will the motor (that is behind a gearbox) just rotate when I apply torque by hand?

Yes, it will rotate, because motor has no power.   Torque limit = 0;