Pressure sensor 89448-34020 for Toyota automobile parts

1. Remote communication

Current (4 to 20 mA) is the preferred analog interface when transmitting information over a long distance. This is because the voltage output is more susceptible to noise interference, and the signal itself will be attenuated by cable resistance. However, the current output can withstand long distances and provide complete and accurate pressure readings from the transmitter to the data acquisition system.

2. Robustness to RF interference

Cable lines are vulnerable to electromagnetic (EMI)/ radio frequency (RFI)/ electrostatic (ESD) interference from adjacent cables and lines. This unnecessary electrical noise will cause serious damage to high impedance signals such as voltage signals. This problem can be easily overcome by using low impedance and high current signals, such as 4-20 mA.

3, troubleshooting

The 4-20 mA signal has a 4 mA output and the pressure value is zero. This essentially means that the signal has a "live zero", so even if the pressure reading is zero, it will consume 4 mA of current. If the signal drops to 0 mA, this function can provide the user with a clear indication of reading error or signal loss. This cannot be achieved in the case of voltage signals, which usually range from 0-5 V or 0-10 V, where 0 V output indicates zero pressure.

4. Signal isolation

The 4-20 mA output signal is a low impedance current signal, and grounding at both ends (transmitting and receiving) may lead to grounding loop, resulting in inaccurate signal. To avoid this, each 4-20 mA sensor line should be properly isolated. However, compared with 0-10 V output, this does prevent the sensor from being daisy-chained to a single cable infrastructure.

5. Receiving accuracy

When transmitting from the pressure sensor, the voltmeter can easily interpret the 0-10 V signal at the receiving end. For 4-20 mA output, the signal can only be read after the receiver is converted to voltage. In order to convert this signal into a voltage drop, a resistor is connected in series at the output terminal. The accuracy of this resistor is very important for the measurement accuracy of the received signal.