EGX100 termination dip switches are set to "on" for termination
When the termination is enabled (On), the EGX applies a 120 ohm resister across the RS485 terminals.
In a 2 wire application the 120 ohm resistor is connected across the positive (+) and negative (-) terminals (In this 2-wire mode the RX+ and TX+ are jumpered together and the RX- and TX- are jumpered together).
In the 4 wire application mode two 120 ohm resistors are connected. One is connected across the transmit plus (TX+) and transmit negative (TX-). The other is connected across the receive plus (RX+) and the receive negative (RX-).
The modbus standard specification requires both sides of a modbus daisy chain to be terminated.