Instructions for 4-20 mAmp measuring converter
The 4-20 mA signal converter is used to integrate third-party sensors into Didactum's Ethernet-based measurement and monitoring systems. The sensor to be integrated must provide output signals in the range of 4 to 20 milliamperes.
You can configure the 4-20 mA signal converter and convert the desired function data via the German-language web interface of your monitoring system.
In addition to data acquisition, the measurement and monitoring systems can also be used for control and regulation purposes. Furthermore, notification and alarm functions are supported via email, SMS (via GSM modem), or SNMP (Simple Network Management Protocol).
4-20 mA signal transmission
Data transmission via 4-20 mA current signals is widely used in measurement technology and industrial automation. The two-wire connection enables simple and reliable operation of current transducers.
Current transducers do not fail in the event of a short circuit and are less susceptible to interference (especially at low load resistances). A two-wire connection is quick to implement and is immune to electromagnetic interference (industrial interference, radio interference).
The 4-20 mA signal transmission serves, among other things:
- as an interface between sensors and transducers for measuring parameters
- supports the exchange of information between individual devices/sensors
The analog signal is represented as direct current in a range of 4-20 mA, where 4 mA corresponds to the minimum signal level and 20 mA to the maximum signal level.
R420 - Ohm resistance of the Didactum 4-20mAmp transducer (load)
Rline1 and Rline2 - Ohm resistance of the (two-wire) cables
Vpower - Voltage of the sensor's power supply
A0 - Analog output
AI - Analog input
Important note:
Check the exact voltage of the sensor's power supply! Please refer to the documentation for the specifications.
Connection diagram of two-wire transducers and two-wire sensors
If the sensor to be integrated does not have its own power supply or if the required voltage is insufficient, please connect a suitable power supply unit.
Note:
To minimize feedback on the power cables, the sensor power supply lines must be connected directly to the positive terminal of the power supply!
The negative wire should be as short as possible.
Connection of multiple sensors to the 4-20mA measuring converter
The diagram below shows how to connect multiple sensors to a single power supply. The analog inputs of the sensor converter (AIine1-AIine3) are passive.
The UDP power supply must provide sufficient voltage to power all sensors (converters).
Example:
If the current draw of one sensor is 24 mA, then the power supply for all three sensors must be at least 72 mA.
Specifications of the Didactum 4-20 mA measuring converter
Dimensions: 6 cm x 1.8 cm x 1.8 cm (L x H x W)
Weight: 0.05 kg
Input: Terminal plug with 2 inputs
Connection: RJ-12 / RJ-11 patch cable
Operating environment: Humidity: Min. 5% - Max. 95% (non-condensing)
Mounting: Surface mounting
Power consumption (typ.): 100 mW
Made in: EU
Maximum placement distance: Up to 50 meters from the measuring and monitoring system
Insulation: Galvanic isolation 1 kV
Measuring range: 4-20 mA
Accuracy: 2%