Application Note

This application note explains how a Senquip ORB or QUAD device can be connected to an active RS485 Modbus network to passively monitor communication between a PLC and a Deep Sea E400 generator controller. Instead of acting as a Modbus master, the Senquip device operates in sniffer mode—listening for valid request/response pairs already occurring on the bus and extracting key operational parameters such as oil pressure, coolant temperature, battery voltage, status LEDs, and control mode. Because the Senquip device never transmits Modbus frames, it has zero impact on the controller, the PLC, or the timing of the existing system. Using a Senquip script and the built-in Modbus parser, the device decodes the returned register data in real time and publishes the values to the Senquip Portal as standard telemetry channels. This provides a reliable and non-intrusive method for gaining visibility into generator behaviour, validating system performance, or adding remote monitoring to installations where active Modbus polling is not practical or not permitted. The approach is easily extended to additional registers or other Modbus-based equipment.

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