King Shell SN-3002-TVOC-N01 TVOC Transmitter (RS485) - 0-60000ppb, 4-20mA/0-5V/0-10V Output, Wall-Mount

The transmitter supports both three-wire and four-wire connections. For a typical three-wire 4-20mA loop, connect the power supply positive (10-30V DC) to the V+ terminal, the ground to the GND terminal, and the current signal output to the Iout terminal. The device acts as a current source, requiring a 250-ohm load resistor at the receiving end (PLC/DCS) to convert the current to a voltage signal.

Connect the RS485 A and B terminals to your host controller's RS485 bus, ensuring proper termination and bias resistors if required for long cable runs. The device uses the Modbus RTU protocol. You will need to configure your SCADA or data acquisition software with the sensor's unique slave address (configurable via internal DIP switches or software) and the relevant holding registers for reading TVOC concentration values and other parameters.

The metal oxide semiconductor (MOS) sensor has a typical operational lifespan of several years under normal environmental conditions. Periodic calibration is recommended for critical applications to maintain measurement accuracy. The sensor features baseline auto-correction, but a manual calibration against a known zero gas (clean air) and span gas can be performed via the Modbus interface or by adjusting onboard potentiometers for analog outputs.

While the housing is IP65 rated (dust-tight and protected against low-pressure water jets), it is primarily designed for wall-mounted indoor use. For outdoor installation, it must be placed under a protective eave or enclosure to prevent direct rainfall, prolonged UV exposure, and condensation, which could affect sensor longevity and performance outside its specified -40°C to +80°C operating range.