| Terms | Applicable Categories |
|---|---|
| Repeater Unit | Networks |
| replace | Programmable Terminals |
| reset | Counters |
| Programmable Terminals | |
| reset method | Measuring / Motor Protective Relays |
| reset resistance | Level Switches |
| reset time | General Purpose Relays |
| residual voltage characteristic | Proximity Sensors |
| resistance thermometer | Temperature Controllers |
| response time | Safety Sensors |
| restart during momentary power interruption | Inverters |
| retroreflective model | Photoelectric Sensors |
| return water | Level Switches |
| reverse | Inverters |
| reverse operation | Temperature Controllers |
| reverse voltage | Push Buttons / Indicator Lamps |
| reversible counter | Counters |
| RFID Systems | RFID Systems |
| ripple | Power Supplies |
| risk assessment | Safety |
| rivet contact | Basic Switches |
| roaming | Wireless Components |
| robust tuning | Temperature Controllers |
| Rotary Encoders | Rotary Encoders |
| rotation direction | Inverters |
| Rotation Direction Limit Selection | Inverters |
| rotational limitation at power failure | Rotary Encoders |
| rotor inertia | Servomotors / Servo Drivers |
| routing table | Programmable Controllers |
| RS, CS, Xon, or Xoff control | Wireless Components |
| RS-232C communications | Inverters |
| RS-422A/485 communications | Inverters |
| RUN mode | Programmable Controllers |
| run/stop switching | Temperature Controllers |
| Rung comment | Programmable Controllers |