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Daviteq 0-20 mA current input
LoRaWAN
Sigfox
Sub-GHz
NB-IoT

Daviteq 0-20 mA current input

MA

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1. Introduction

Overview

Daviteq 0-20 mA current input (MA) node to connect to 0-20mA DC current from Process instruments like Pressure transmitter, Temperature transmitter, Level transmitter, Flow meters, Analyzers... at very low voltage drop. The MA node can be integrated into the wireless transmitter from Daviteq, such as Sub-GHz WS433, LoRaWAN WSLRW, and Sigfox WSSFC, to build the complete Wireless 0-20 mA current input node. The MA node is also powered by the batteries or external power. The MA could ouput voltage to supply power for 0-20 mA sensor

Specification

Measuring range: 0 .. 20mA

Accuracy: 0.05% of span

Resolution: 1/3000

Temperature drift: < 50ppm

2. Principle of Operation

With ADC module, the MA node transform the 0-20 mA input from sensor to digital value


The MA Node could work in loop powered sensor or non-loop powered sensor based on wirings and configuration



3. Calibration

The MA Node is calibrated by following steps:

  • Note out the current coefficient A and constant B. A and B is in formula: Y = A *X + B where X is raw value and Y is mA

  • Set the coeffiecent A=1 and constant B=0 to the MA node memory

  • Connect the calibration current source to the MA node

  • Set the calibration current source to a low value ( 0mA ) and note out the X1 value

  • Set the calibration current source equal to 20mA and note out the X2 value

  • Calculate A, B based on formula:

    0 = A*X1 + B and 20=A*X2 +B

  • Write calculated A, B to the MA node memory

  • Set alibration current source 0mA and 20 mA and check the value output to make sure the A, B is written properly

4. Application Notes

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5. Installation Notes

  1. Recommend using the shielded cable with twisted pairs;

  2. Avoid the installation near by the high magnetic field like high power Motors, Transformers, and Power Generator.

  3. Following right wiring connections based on 0-20 mA sensor


Note:

DO NOT CONNECT AN EXTERNAL POWER SUPPLY TO THE PWR + WIRE OF THE WIRELESS SENSOR !!!

SUPPLYING AN EXTERNAL POWER SUPPLY TO THE SENSOR'S PWR + LINE CAN MAKE SERIOUS DAMAGE !!!


4. Following wiring label as below



6. Troubleshooting

The output value is always zero

  • The sensor cable is broken

  • No 0-20 mA sensor is installed

  • Loose connection between the MA node and 0-20 mA sensor

  • The 0-20 mA sensor is defective

  • The MA node is defective

  • High cut setting is configured to 0


The output value of the MA Node sometimes fluctuate when mA input is unchange

  • Loose connection between the MA node and 0-20 mA sensor

  • The 0-20 mA sensor is defective

  • The MA node is defective



7. Maintenance

  • There are no moving parts or consumed parts in the MA Node. Therefore there is no need to do maintenance.

  • However, depending on the installation environment, the MA Node must be checked periodically for accurate ADC converter.

8. Default Configuration