The Advantech/B&B Electronics 485SD9R is a port-powered RS-232 to RS-485 converter that enables bidirectional communication between RS-232 devices and RS-485 networks without requiring an external power supply. Power is derived directly from RS-232 handshake lines (DTR, RTS, DSR, CD), consuming less than 3 mA, making it ideal for applications where auxiliary power is unavailable or impractical.
Technical Specifications
Interfaces & Connectors
• RS-232: DB-9 female; TD (pin 3) and RD (pin 2) passed through; handshake lines tied for power and loopback
• RS-485: DB-9 female; 2-wire, half-duplex operation
• Data Rate: Up to 115.2 kbps
• Maximum Distance: 1.2 km (4,000 ft) at 19,200 baud
• Operating Temperature: 0°C to 70°C
Electrical
• Power Source: Port-powered via RS-232 handshake lines
• Power Consumption: Less than 3 mA plus load current
• Transient Suppression: Built-in protection against voltage spikes
– Key Features
• Automatic Send Data Control: Hardware-based mechanism that automatically enables the RS-485 driver when data transmits and disables it when idle. The receiver is disabled during transmission to prevent echo, eliminating dependence on software drivers or RTS signal manipulation—a critical advantage on modern operating systems.
• Multi-drop Capable: RS-485 protocol supports multi-drop network configurations.
• Power Efficiency: Optimized performance when handshake lines are raised and no termination is applied.
– Typical Applications
The 485SD9R addresses communication challenges in industrial control systems, remote monitoring stations, and legacy equipment integration where RS-232 devices must interface with RS-485 networks. Its port-powered design is particularly suited to installations with power constraints or distributed node architectures.
– Compatibility & Integration
Direct compatibility with any RS-232 host and RS-485 slave or multi-drop networks. DB-9 connectors support standard cabling and field termination. Hardware-based driver control operates independently of host operating system or serial port driver configuration.
