The combustible gas detector has two signal outputs: analog 4-20mA output and RS-485 data bus output. The 500 model only has a 4-20mA output. The output signal is a 4-20mA linear analog signal related to the detection range. This signal is compatible with 10 series and 12 series multi-module controllers, programmable logic controllers and other standard data acquisition equipment. The analog output has two other functions. 1. When entering the calibration menu, the 4-20mA signal will drop to 2mA. The low current will be maintained until the sensor returns to a normal operating state. Second, once an error occurs, the 4-20mA signal will drop to 0mA, and this condition will remain until the error state returns to normal. The changes of these output signals can be used by external equipment to identify and record the working status of the sensor.
The Modbus RTU protocol is used in RS-485 data communication, which is compatible with almost all programmable logic controllers, man-machine interface software and other control systems. Because the Modbus RTU protocol is a standard. The following information can be obtained from the RS-485 communication interface: detector readings, detector alarm points, calibration mode, detector error, two alarm status and calibration procedure error. The RS-485 address can be changed by the dual in-line package switch. The communication is two-wire, half-duplex, and there is a detector as its servo equipment. In theory, the main controller can simultaneously control 256 different detectors at a distance of 4000 feet.
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