Proline Promass 83E/F/O Modbus RS485 Operating Instructions

OperationProline Promass 83 Modbus RS485#Warning!5.7.3 Configuring the terminating resistorsIt is important to terminate the Modbus RS485 line correctly at the start and end of the bus segmentsince impedance mismatch results in reflections on the line which can cause faulty communicationtransmission.Risk of electric shock. Exposed components carry dangerous voltages.Make sure that the power supply is switched off before you remove the cover of the electronicscompartment.The miniature switch for termination is located on the I/O board (see Figure):Fig. 38: Configuring the terminating resistorsA = Factory settingB = Setting at the last transmitter!Note!It is generally recommended to use external termination since if a device that is terminatedinternally is defect, this can result in the failure of the entire segment.Page 56 • MN0M030Issue/Rev. 0.2 (12/12)