Configured for specialized point-to-point data exchange, the Yokogawa ALR111-S50 (ALR111) Serial Communication Module provides direct physical electrical execution for RS-232C-based device interfacing within CENTUM VP and ProSafe-RS control architectures.

Hardware Specifications

Communication Architecture and Signal Integrity

The ALR111-S50 utilizes a start-stop synchronization method for binary data transmission. It is engineered for deterministic serial communication, supporting various baud rates and parity configurations to match specific field instrument requirements. Due to the inherent nature of the RS-232C standard, communication is limited to a 15-meter transmission distance to ensure signal voltage levels remain within valid logical thresholds, preventing bit-errors caused by line capacitance and attenuation.

Frequently Asked Questions

Q: Does the ALR111-S50 support full-duplex communication?

A: No, the module is specifically configured for half-duplex communication, meaning data can be transmitted or received, but not simultaneously, following the logic requirements of the connected field subsystem.

Q: Can this module be used in hazardous locations?

A: The "S50" suffix denotes that this module does not have explosion protection. It must be installed in a non-hazardous, controlled environment or shielded appropriately if required by local process safety regulations.

Field Installation Guidelines

• Secure the D-sub 9-pin connections firmly; the module relies on stable physical contact to maintain the RS-232 voltage levels required for reliable bit-level data exchange.
• Use high-quality, shielded serial cables; keep cable runs under the 15-meter limit to minimize signal degradation and susceptibility to external electromagnetic interference (EMI).
• Ensure that the communication parameters (baud rate, parity, stop bits) are identical in both the ALR111 software configuration and the connected field device to prevent communication timeouts.
• Route serial lines away from high-power AC cabling and variable frequency drives (VFDs) to mitigate the risk of induced noise, which can cause intermittent communication frame errors.