This dual-port serial communication module provides flexible connectivity for Yokogawa control systems. The ALR121-S01 integrates RS-232-C and RS-422/485 interfaces in a single compact unit. It enables simultaneous communication with printers, operator stations, and field instruments. System integrators choose this module for its dual-port design and reliable data transfer. Its single-slot format optimizes rack space in Centum VP and ProSafe-RS systems.
Technical Specifications Summary
| Parameter | Specification |
|---|---|
| Communication Interfaces | 1x RS-232-C, 1x RS-422/485 (software-selectable) |
| Data Rate | 300 bps to 38.4 kbps, independently configurable per port |
| Data Bits | 7 or 8 bits per character |
| Stop Bits | 1 or 2 stop bits |
| Parity Options | None, odd, even, mark, or space |
| Flow Control | RTS/CTS hardware and XON/XOFF software |
| Supported Protocols | ASCII, MODBUS RTU, and user-defined protocols |
| Transmit Buffer | 256-byte FIFO per communication port |
| Receive Buffer | 256-byte FIFO per communication port |
| Isolation Voltage | 1500 V RMS between ports and logic circuitry |
| Connector Type | 9-pin D-sub (RS-232), 5-pin terminal (RS-422/485) |
| RS-485 Mode | 2-wire half-duplex or 4-wire full-duplex |
| Termination Resistors | Built-in, software-selectable for network integrity |
| Maximum Cable Length | 15 meters (RS-232), 1200 meters (RS-422/485) |
| LED Indicators | Power, TX, RX, and error status per port |
| Dimensions (H x W x D) | 130 mm x 40 mm x 120 mm |
| Weight | 0.35 kg |
| Power Consumption | 4 W from +5 V DC backplane |
| Operating Temperature | -10 °C to +55 °C |
| Storage Temperature | -40 °C to +85 °C |
| Relative Humidity | 10% to 90% non-condensing |
Dual-Port Interface and Independent Operation
The module features two independent serial ports with distinct physical layer standards. Port 1 offers a standard RS-232-C interface for point-to-point device connections. Port 2 provides RS-422 or RS-485 capability for long-distance and multidrop networks. The ALR121-S01 configures each port’s parameters independently through software. Users set baud rate, data bits, parity, and flow control per channel separately. The module applies these settings to each port without cross-interference. This independent operation accommodates two different device types on one module.
RS-422/485 Long-Distance and Multidrop Capability
The RS-422/485 port supports communication over extended distances up to 1200 meters. This port handles multidrop networks with up to 32 devices on a single bus. The ALR121-S01 offers both 2-wire half-duplex and 4-wire full-duplex configurations. Users select the operating mode through the module’s configuration interface. Built-in termination resistors ensure signal integrity on long cable runs. The software-selectable resistors eliminate the need for external termination components. This capability suits distributed plant layouts and remote I/O applications effectively.
Buffering and Data Flow Management
The module provides 256-byte FIFO buffers for transmit and receive operations on each port. These buffers accommodate burst data transmissions without losing characters. The ALR121-S01 supports both hardware and software flow control methods comprehensively. RTS/CTS handshaking provides reliable pacing for high-speed data transfer. XON/XOFF software control works effectively with simpler cable configurations. The module monitors buffer levels and manages data flow automatically to prevent overruns. These features ensure reliable communication with various peripheral devices.
Protocol Support and Diagnostic Tools
The module supports ASCII and MODBUS RTU protocols for standard industrial device communication. ASCII protocol interfaces with terminals, printers, and simple data acquisition devices. MODBUS RTU enables integration with analyzers, transmitters, and PLC systems. The ALR121-S01 also allows user-defined custom protocols for specialized applications. Engineers implement custom protocols through the host controller’s programming environment. A loopback test mode facilitates installation verification and fault isolation. This protocol flexibility adapts to both legacy and modern system architectures.
Connector Types and Diagnostic Indication
Distinct connector types provide clear physical differentiation between the two ports. A 9-pin D-sub connector serves the RS-232 interface for standard peripheral cabling. A 5-pin terminal block provides access to the RS-422/485 port for field wiring. The ALR121-S01 provides 1500 V RMS isolation between both ports and system logic. This isolation protects the controller from ground loops and voltage surges. LED indicators display power, transmit, receive, and error status for each port independently. These diagnostics simplify installation verification and ongoing maintenance activities.
Mechanical Construction and Environmental Performance
The module features a lightweight design for straightforward rack installation. It measures 130 millimeters high, 40 millimeters wide, and 120 millimeters deep. The unit weighs 0.35 kilograms for convenient handling and insertion. Power consumption reaches 4 watts from the +5 V DC backplane supply. Operating temperature spans -10 °C to +55 °C for control room applications. Storage conditions range from -40 °C to 85 °C for logistics protection. Humidity tolerance covers 10% to 90% without condensation affecting circuit operation.
Details
| Weight | 0.35 kg |
|---|---|
| Dimensions | 130 × 40 × 120 mm |
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