Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [4-20ma]

In industrial environments 4-20mA is a commonly used range of values for a current loop where 4mA represents the lowest value and 20mA indicates the maximum. Some advantages compared to sending a voltage is that the resistance of the cable doesn't affect accuracy and devices may be powered from the same pair of wires.

In industrial environments 4-20mA is a commonly used range of values for a current loop where 4mA represents the lowest value and 20mA indicates the maximum. Some advantages compared to sending a voltage is that the resistance of the cable doesn't affect accuracy and devices may be powered from the same pair of wires. While probably most often associated with sensors they may also be used to control actuators.

Devices that supply power to other devices may be described as active while devices that rely on power being delivered may be described as passive. The Wikipedia Current loop article provides further information on common applications and configurations for current loops.

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Best practice in transmitting sensor analog signal over longer distances (approx. 100') -- in cost sensitive products for microcontrollers

I'm looking for best practices for transmitting an analog sensor signal over long distances to a microcontroller such as the Arduino running at 3.3v or 5v. Keeping costs low is imperative. SPI and I2C is very common in Arduino land, but it seems…
risingtiger
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how to connect 4-20mA signals to my PC

I'd like to run some tests by using 4-20mA sensors outputs, by somehow connecting them to my PC (and eventually run some analysis on the collected data). I'm looking for a converter (that can perhaps be plugged in via USB), or some other interface…
amiram
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4 to 20ma current loops - best power and receiver practices?

A customer wants me to add an expansion board to my industrial computing platform to handle multiple 4 to 20ma loops. Currently, he wants to power the loop and receive data from transducers. I've done a little research, and I've found that typically…
darron
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4-20 mA to 0-3.3V converter

I have a 4-20mA signal and want to feed it to my uC. I found this circuit but dont know how it works. can any one explain this for me? or suggest a better solution
reza moslemi
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Using a microcontroller ADC to measure a 4-20mA sensor

Question from a SW Engineer again. I've got a device which is mains powered and outputs a 4-20mA current depending on the flow rate in a pipe. I'd like to measure that flow rate with a microcontroller. On the face of it it's easy. My microcontroller…
jwhitmore
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4-20 mA current source

TLDR: given a sensing device that produces a varying resistance, how does a "sensor" change this into a 4-20 mA current flow from a 24 V supply? Various sensors (flow, fluid depth, ...) use a 4-20 mA output to convey their measurements: you put +24V…
John
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How does a 4-20mA bus powered sensor work?

I need to build a circuit that has 4-20mA input and can power sensors from the loop with 2-wire connection. Could someone explain the principle of the power circuit built in such sensors? I would be grateful if someone drew a simplified…
Kamil
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Automotive Sensor Output

Why does the automotive industry sticks with 5V sensor outputs instead of something like 4-20 mA? Wouldn't it be a solution less prone noise? What are the advantages in using a 5V output instead of a current signal?
Manzillo
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Controlling a 0-20mA transmitter from an isolated PWM signal

I'm trying to generate a 0-20mA signal for controlling an industrial actuator (the position of a 3-way valve) from a Teensy 3.2 system. Preferably, the mA-output should be galvanically isolated from the microcontroller to protect it properly. In…
Johan E. T.
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4-20mA current loop design

I have been working on 4-20mA transmitter project and stuck with a problem. My design is based on CN0319 evaluation board but I changed some of it, to make it works with other part of the design. Below is my design, I want it to transmit 4-20mA…
LazyLabor
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Analyze of 4-20mA circuit

I'm looking at the 4-20mA circuit below and trying to understand it. For some reason I can't get this to click in my mind. Pressure sensor is a Metallux ME751 with a supply voltage of 9..35 VDC and it outputs 4-20mA. From my point of view (please…
RedSmolf
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Need more current than 4 mA in 4/20mA loop current

We know that in a 4/20 mA loop current, 4 mA represent 0% and 20 mA represent 100%. For loop current we use an IC like XTR115, and my circuit is fed from this IC. If my circuit needs higher current than 4 mA to run, how can I obtain it?
Rashid
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Drive LEDs from 4-20mA source

I have a task to drive four LEDs from a 4-20mA loop. I have 24V for the LED side so I need to convert the current into something that can drive the LEDs. I know I can use a 250\$\Omega\$ resistor as the converter in the loop which will give me 1-5V…
user3047
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How to acquire current values in data acquisiton accurately when using a shunt resistor in a current loop?

Here is the setup I use. Since the DAQ system is only able to read voltages first I record the voltages by a shunt resistor. But I need the "current values" at the end. Transducer will make the current vary between 4 to 20 mA. If the resistance is…
user16307
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Using an optocoupler to separate a 4-20 mA loop

I have a PLC that is powered with 3.3 V and a sensor powered with 12 V that outputs a 4-20 mA signal. In order to allow the signal to be readable by my PLC while isolating the current in the 12 V loop from the 3.3 V loop I need to use an…
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