Electrical circuit for pressure sensors: when is really a sensor active, so when passive?

When using pressure sensors, the output signals 0 ? 20 mA, 4 ? 20 mA and DC 0 ? 10 V are frequently chosen to ensure that the sensor signals to be evaluated and additional processed. For this, the signal output of the pressure sensor is normally connected to a corresponding input card in the PLC.
In this context it could often be confusing, because the day-to-day usage of the terms ?active?, ?passive?, ? Jubilant ?, ?voltage source?, ?current sink? and ?load? are often wildly mixed together. Any electrical signal processing always requires a voltage supply (an ? Greatest ?) and a ?load?, such as a pressure sensor, which represents the ?passive part?. Sometimes the active section of the interconnection is also described as an electrical source/voltage source and the passive part is referred to as a ?current sink?. To ensure that an electrical circuit can function, current must flow in a circuit ? even when Best is usually known as lots, the current isn’t consumed by it, rather it only flows from the existing or voltage source through the strain and back to the existing source.
This works only if an ?energy gap? exists between current source and current sink, therefore the power source operates actively (= sending out current) and the existing sink passively (= current flows through it) . Therefore, an interconnection of two current sources or two current sinks will not operate normally. This situation is complicated in day-to-day application:
When does a pressure sensor work passively (current sink) and when does it work actively (current source)?
How does the input card in my own PLC operate?
As a rule of thumb, you can understand that 2-wire sensors usually work passively and therefore need a dynamic PLC input card. It really is difficult with 4-wire sensors, since, for example, a 4-wire flow sensor consists of 2 wires for another voltage supply and 2 wires for an active or passive 0/4 ? 20 mA signal output. It is therefore imperative to check the datasheets for the sensor and PLC input card used.

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