Modbus RTU (RS485) connection

The Link supports communication with external installation components via the Modbus RTU protocol. To establish a reliable connection, all devices on the network must "speak the same language" by sharing identical communication settings.

1. Record the serial settings. First, consult the manufacturer's user manual for each external Modbus device and record the following serial communication parameters. These must be consistent across your entire network.

   • Baud rate: the speed of communication (e.g. 9600 bps).
   • Data bits: the number of data bits in each character (typically 8).
   • Parity: the method of error checking (e.g. none, even, odd).
   • Stop bits: the bits that signal the end of a character (typically 1).

   Same settings on every device

   Different settings: not allowed

   The Link only has a single RS485 port. If the characteristics of the installation components require to set more than two homogeneous networks, due to different baud rates, then an additional Link is required.

2. Wire the serial network.

   In a chain, from device to device

   In a star: not allowed

   The end nodes in an RS485 network must have a 120 ohm resistor between the A and B or the (+) and (−) terminals.

3. Connect the network to the RS485 port of the Link.

   Ensure correct polarity. Connect the positive A/+ terminal to positive A/+ and the negative B/− terminal to negative B/−. Reversing these connections can lead to communication failure or equipment malfunction.