Hi Sneha,
The "R" port in the DC motor is a mechanical rotational conserving port. It does not directly measure anything. So you cannot take out this terminal through a PS-Simulink converter directly. However, you can connect it to any sensor to measure rotational motion, linear motion, or position and connect it to a PS-Simulink converter before connecting it to a Simulink outport.
The "S" block is like a subsystem within which there is a sensor sensing the rotational speed of the rotor in rpm, which is then connected to a PS-Simulink converter before connecting to the outport. You can find this example containing a similar "S" block for your reference.
If you need to take out the "R" terminal crossing a subsystem boundary, you can use Connection ports. You can find more details on them here.
You can find more information on the DC motor in the following documentation.
Hope this answers the query.
