This dual-port serial communication module expands connectivity options for Yokogawa control systems. The ALR121-S00 provides both RS-232-C and RS-422/485 interfaces in a single compact unit. It facilitates data exchange between Centum VP controllers and diverse field devices simultaneously. Control engineers select this module for its dual-port flexibility and reliable performance. Its single-slot design conserves valuable rack space in Yokogawa chassis configurations.
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, per-port configuration |
| 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 |
| Protocol Support | ASCII, MODBUS RTU, 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 system logic |
| 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 | Built-in software-selectable termination resistors |
| Max Cable Length | 15 m (RS-232), 1200 m (RS-422/485) |
| LED Indicators | Power, TX, RX, and error 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 Architecture and Independent Configuration
The module integrates two independent serial ports with distinct physical interfaces. Port 1 provides a standard RS-232-C connection for point-to-point peripheral communication. Port 2 supports RS-422 or RS-485 operation for long-distance multidrop networks. The ALR121-S00 configures each port independently through software settings. Users select baud rate, data format, parity, and flow control per channel. The module applies these settings separately to each port without interference. This independent configuration accommodates diverse device types on the same module.
RS-422/485 Long-Distance and Network Capability
The RS-422/485 port enables communication over extended cable distances up to 1200 meters. This port supports multidrop networks with up to 32 connected devices. The ALR121-S00 offers both 2-wire half-duplex and 4-wire full-duplex modes. Users configure the operating mode through the module’s setup interface conveniently. Built-in software-selectable termination resistors ensure signal integrity on long runs. The module automatically handles bus arbitration in multidrop configurations. This long-distance capability suits distributed plant installations effectively.
Data Buffering and Flow Control Features
The module provides 256-byte FIFO buffers for transmit and receive operations per port. These buffers prevent data loss during high-speed or burst communications. The ALR121-S00 supports both hardware and software flow control methods. RTS/CTS handshaking manages data flow reliably for high-speed connections. XON/XOFF software control suits simpler cabling installations effectively. The module monitors buffer levels and manages data flow automatically. These features ensure smooth, error-free communication across both ports.
Protocol Support and Custom Implementation
The module supports ASCII and MODBUS RTU protocols for standard device compatibility. ASCII protocol interfaces with terminals, printers, and basic data loggers. MODBUS RTU enables integration with industrial instruments and analyzers. The ALR121-S00 also accommodates user-defined custom protocols for specialized needs. Engineers program these protocols through the host controller’s development environment. A built-in loopback test mode simplifies installation verification and troubleshooting. This protocol flexibility adapts to diverse automation system requirements.
Physical Interface and Diagnostic Capabilities
Distinct connectors provide physical access to each communication port conveniently. A 9-pin D-sub connector serves the RS-232-C interface for peripheral connections. A 5-pin terminal block provides RS-422/485 wiring access for field cabling. The ALR121-S00 provides 1500 V RMS isolation between both ports and the system logic. Front-panel LEDs indicate power, transmit, receive, and error status for each port. These indicators simplify installation verification and ongoing system maintenance. All connectors include strain relief for robust field installation.
Mechanical Construction and Environmental Tolerance
The module features a compact, lightweight design for straightforward installation. It measures 130 millimeters high, 40 millimeters wide, and 120 millimeters deep. The unit weighs 0.35 kilograms for convenient handling during installation. Power consumption reaches 4 watts from the +5 V DC backplane supply. Operating temperature spans -10 °C to +55 °C for typical control room environments. Storage conditions range from -40 °C to 85 °C for shipping and warehousing. Humidity tolerance covers 10% to 90% without condensation affecting performance.
Details
| Weight | 0.35 kg |
|---|---|
| Dimensions | 130 × 40 × 120 mm |
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