Yokogawa ALR121-S01 Serial Communication Module
Configured for serial data exchange in ProSafe-RS control platforms, the Yokogawa ALR121-S01, also cataloged as the ALR121-S01 Serial Communication Module, provides direct physical/electrical execution.
Hardware Specifications
| Parameter | Specification |
|---|---|
| Model | ALR121-S01 |
| Brand | Yokogawa |
| Origin | Japan |
| Weight | 0.34 kg |
| Dimensions | Standard Yokogawa slot width |
| Operating Temp | 0 to 55 deg C |
| Power Consumption | 0.5 A (current consumption) |
| Interface | RS-422, RS-485 (4-wire system) |
| Max Transmission Distance | 15 m (RS-422), 1200 m (RS-485) |
| Transmission Speed | 1200 / 2400 / 4800 / 9600 / 19200 / 38400 bps |
| Connection Type | 2x D-sub 9-pin female or 2x M4 screw terminal block (5 poles) |
| System Compatibility | S2SC70S, SSC60S, SSC50S, SSC57S, SNB10D |
Channel-to-Channel Isolation and Serial Protocols
The Yokogawa ALR121-S01 module incorporates half-duplex RS-422 and RS-485 serial interfaces designed for Modbus slave and subsystem communication. Integrated isolation circuitry mitigates ground potential differentials and common-mode transients between the Safety Control Station (SCS) sub-rack and external Modbus master devices. Supporting start-stop synchronization and configurable parity control, the module maintains signal stability across transmission distances up to 1200 m on RS-485 networks in high-density process automation environments.
Frequently Asked Questions
Q: What are the wiring connection limits when using the ALR121-S01 RS-485 interface?
A: The RS-485 multipoint connection supports a maximum cabling distance of 1200 m using standard 4-wire shielded twisted-pair cabling with appropriate terminal line termination resistor matching.
Q: Can the ALR121-S01 be installed into a live safety control unit baseboard?
A: Module insertion or removal must comply with Yokogawa ProSafe-RS rack power down requirements or designated hot-swap procedures to prevent bus logic interruptions and field transceiver damage.
Field Installation Guidelines
- Isolate main sub-rack power prior to placing the ALR121-S01 into base units such as S2SC70S or SSC60S.
- Terminate signal lines at M4 screw terminal blocks with a recommended torque of 1.2 N m or secure D-sub 9-pin connectors via locking screws.
- Apply standard 120 ohm line termination resistors at both physical endpoints of the RS-485 4-wire serial segment.
- Connect cable shield drains to the local safety chassis ground bar at a single point to avoid earth loop current coupling.
- Maintain dedicated wire routing channels to segregate low-voltage RS-422/RS-485 serial lines from AC power and high-current relay cabling.
Yokogawa ALR121-S01 Serial Communication Module
Yokogawa ALR121-S01 Serial Communication Module
Configured for serial data exchange in ProSafe-RS control platforms, the Yokogawa ALR121-S01, also cataloged as the ALR121-S01 Serial Communication Module, provides direct physical/electrical execution.
Hardware Specifications
| Parameter | Specification |
|---|---|
| Model | ALR121-S01 |
| Brand | Yokogawa |
| Origin | Japan |
| Weight | 0.34 kg |
| Dimensions | Standard Yokogawa slot width |
| Operating Temp | 0 to 55 deg C |
| Power Consumption | 0.5 A (current consumption) |
| Interface | RS-422, RS-485 (4-wire system) |
| Max Transmission Distance | 15 m (RS-422), 1200 m (RS-485) |
| Transmission Speed | 1200 / 2400 / 4800 / 9600 / 19200 / 38400 bps |
| Connection Type | 2x D-sub 9-pin female or 2x M4 screw terminal block (5 poles) |
| System Compatibility | S2SC70S, SSC60S, SSC50S, SSC57S, SNB10D |
Channel-to-Channel Isolation and Serial Protocols
The Yokogawa ALR121-S01 module incorporates half-duplex RS-422 and RS-485 serial interfaces designed for Modbus slave and subsystem communication. Integrated isolation circuitry mitigates ground potential differentials and common-mode transients between the Safety Control Station (SCS) sub-rack and external Modbus master devices. Supporting start-stop synchronization and configurable parity control, the module maintains signal stability across transmission distances up to 1200 m on RS-485 networks in high-density process automation environments.
Frequently Asked Questions
Q: What are the wiring connection limits when using the ALR121-S01 RS-485 interface?
A: The RS-485 multipoint connection supports a maximum cabling distance of 1200 m using standard 4-wire shielded twisted-pair cabling with appropriate terminal line termination resistor matching.
Q: Can the ALR121-S01 be installed into a live safety control unit baseboard?
A: Module insertion or removal must comply with Yokogawa ProSafe-RS rack power down requirements or designated hot-swap procedures to prevent bus logic interruptions and field transceiver damage.
Field Installation Guidelines
- Isolate main sub-rack power prior to placing the ALR121-S01 into base units such as S2SC70S or SSC60S.
- Terminate signal lines at M4 screw terminal blocks with a recommended torque of 1.2 N m or secure D-sub 9-pin connectors via locking screws.
- Apply standard 120 ohm line termination resistors at both physical endpoints of the RS-485 4-wire serial segment.
- Connect cable shield drains to the local safety chassis ground bar at a single point to avoid earth loop current coupling.
- Maintain dedicated wire routing channels to segregate low-voltage RS-422/RS-485 serial lines from AC power and high-current relay cabling.
