Technical Specifications:

• Module Type: RS-485 Serial Communication
• Communication Protocol: Modbus RTU (Master/Slave)
• Number of Ports: 1 × RS-485 (2-wire half-duplex)
• Baud Rate: 9600, 19200, 38400, 57600, 115200 bps (selectable)
• Data Format: 8 data bits, 1 stop bit, No parity / Even parity / Odd parity (selectable)
• Max Communication Distance: 1200 m (at 9600 bps)
• Isolation Voltage: 500 VDC (between PLC bus and RS-485 port)
• Power Supply: 5 VDC from PLC backplane bus
• Current Consumption: 120 mA (typ.) from backplane
• Operating Temperature: 0°C to +55°C (+32°F to +131°F)
• Dimensions (W × H × D): 25 mm × 90 mm × 85 mm
• Weight: Approximately 0.08 kg

Functional Features:

• Supports Modbus RTU master and slave modes simultaneously
• Up to 32 Modbus registers for data exchange (configurable)
• Built-in termination resistor switch (120 Ω)
• LED indicators for TX, RX, and error status
• Hot-swappable from the PLC rack

Structural Features:

• Standard F3/F4 series module form factor
• DIN rail mountable within PLC rack
• Terminal block connector for RS-485 A/B lines
• Termination resistor DIP switch on module

Working Principle:
The module interfaces with the PLC CPU via the backplane bus. The CPU sends/receives Modbus RTU frames to/from the RS-485 port. The module handles all serial protocol timing, CRC calculation, and frame formatting. In master mode, the PLC polls slave devices; in slave mode, the module responds to queries from an external master. The RS-485 transceiver provides differential signaling for noise immunity over long cable runs.

Advantages & Highlights:

• Wide baud rate selection up to 115200 bps for high-speed data exchange
• Galvanic isolation of 500 VDC protects the PLC from ground loops and surges
• Dual-mode operation (master/slave) provides maximum integration flexibility
• Compact form factor fits standard F3/F4 PLC racks

Applicable Industries:

• All industries using F3/F4 series PLCs
• Building automation (BACnet-to-Modbus gateways)
• Water/wastewater SCADA integration
• Packaging machinery

Installation Requirements:

• Insert into the F3/F4 PLC rack at the designated slot position
• Set the termination resistor switch to ON for the last device on the RS-485 bus
• Use shielded twisted-pair cable (120 Ω characteristic impedance)
• Connect A (+) and B (-) terminals correctly; reverse polarity causes communication failure

Usage Precautions:

• Maximum 32 devices (including master) on a single RS-485 segment without repeaters
• Do not mix 2-wire and 4-wire RS-485 devices on the same bus
• Set the baud rate, parity, and stop bits identically on all devices on the bus
• Keep RS-485 cable away from high-power cables (minimum 200 mm separation)