Use recorder to record switch signal

The recorder records the switch value to determine whether the switch value is active or passive. Active means that the output has voltage, the circuit itself has a power source, and passive means that the output has no voltage. There are 5 ways to choose from to record the switch signal. Mainly related to instrument configuration and wiring issues. In the case of active: The first method: use a transmitter, such as an active signal voltage of 220V, then it can be converted into 0-5V or a signal that can be received by some other standard recorder (0-10V) through a voltage transmitter , 4-20mA, etc.), the recorder configuration is set to 0-5V input, the range corresponds to 0-1, the switch can be stringed into the loop on the wiring, and it can be connected to the corresponding terminal of the recorder. That is, when the switch is off, the recorder displays 0, then 0 represents disconnection, and when the recorder displays 1, 1 represents closed. The second method: use relays. Connect the on-site switching signal to be recorded to the relay, and connect the 220V power supply to the circuit in series. Since the relay outputs a switching signal, it is equivalent to changing the active signal into a passive signal. Passive Three ways to record the situation. Not directly through the alarm output. Passive case: The third method: when the switching value is without voltage, then the 0-5V or 0-10V switching power supply can be used as the power supply in the same way as the first method, and the switching value signal string is connected to the wiring. In the loop, connect to the corresponding terminal of the recorder. The instrument configuration is set to the corresponding signal input, such as 0-5V, and the range is set to 0-1V, then 0 represents disconnection, and 1 represents closed. The fourth method: use thermocouple signal input, for example, the instrument is set to K-type thermocouple signal, the range is set to 0-1, the principle is to connect the recorder and the switch in series, and the recorder is set to the starting point of disconnection in the configuration , When the switch is disconnected, the recorder will display 0, which means the disconnected state; if it is closed, then the wiring will short-circuit the voltage to the ground terminal, this time means the cold junction temperature, because the cold junction temperature If the maximum range set by the recorder is exceeded, the recorder will display 1, which means that the switch is closed. The fifth method: use the thermal resistance signal input, a 250 ohm resistor in the loop, the meter configuration is set to pt100, the range is set to 0-409 ℃, because 409 ℃ corresponds to the resistance value of pt100 is 250 ohms, the instrument cluster The disconnection in the state is set to the starting point. When the switch is disconnected, the recorder will display 0; if the recorder displays 409, it means that the loop is open and the loop resistance is 250 ohms, which means that the switch is closed. state.