[ENG] [886A02] Loop/Sensor Connection to the Converter
Functions of the converter`s connectors
+24V and +12V — connectors which can give power to the sensor or loop;
RS+ and RS- — «meter» connectors;
GND — common connector.
General information
The main purpose of the converter is to measure the current flowing in the loop. Additionally, the converter can measure the voltage on RS + and calculate the resistance based on the obtained values.
There are two possible schemes of connection:
Low-side — measuring only the flowing current. Voltage is not measured, resistance is not calculated. The loop is closer to the power connector, the shunt is on the GND side.
High-side — measuring the flowing current and voltage, calculation of resistance. Voltage measurement error is up to 60 mV at 30 mA. The loop is closer to GND, the shunt is on the side of the power connector. This scheme is preferred.
The loop connection must always be in direct polarity - current must flow from RS+ to RS-. Reverse polarity connection will not damage the device, but the measurement will be incorrect.
The example of connection
For convenience and clarity, we take a 10 kOhm variable resistor as a sensor, connected according to the High-side scheme.
Thus, with the "middle" position of the resistor handle: 23,900 mV/4.86 mA = 4918 Ohm.
At the "ultimate" right position: 24,000 mV/2.4 mA = 10,000 Ohm.
Attention!
In case of a short circuit at the output of the current loop power of the converter, it goes into protection. No further recovery is possible without a power reset.
It is possible to measure voltage (0...30V) by connecting the + of the power supply to the RS + connector and connecting the GND of the power supply and the converter.
If you connect it this way, only voltage will be measured.
Equivalent circuit scheme of a meter input