OEM LoRaWAN 4-20mA Converter Manufacturer | Industrial IoT

2026-09-07 09:41:49 · Views 17

Factories, farms, water facilities and remote infrastructure often contain reliable instruments that produce a 4–20 mA analog signal. Pressure transmitters, level probes, flow instruments and process-temperature transmitters may continue operating for years, yet their data remains unavailable outside a local control panel.

Replacing every instrument with a new wireless sensor is not always practical. A LoRaWAN 4-20mA converter can read the existing current-loop signal, translate it into an engineering value and transmit compact data to a remote platform.

This approach can add wireless monitoring without changing the primary sensing instrument. It is especially useful where installing new communication cables, Ethernet infrastructure or individual cellular modems would be difficult.

For an OEM project, however, connecting an analog input to a LoRaWAN radio is only the beginning. Input accuracy, electrical protection, loop power, isolation, sensor warm-up, calibration, payload design, gateway coverage and platform integration must be planned as one system.

What Is a LoRaWAN 4-20mA Converter?

A LoRaWAN 4-20mA converter is an industrial IoT device that measures the current generated by an analog transmitter and sends the resulting data through a LoRaWAN network.

A typical architecture is:

Industrial Transmitter → 4–20 mA Input → LoRaWAN Converter → Gateway → Network Server → Application Platform

The converter can be designed to report:

Raw loop current
Scaled engineering value
Percentage of measurement range
High and low alarms
Rapid-change events
Input fault status
Battery or supply voltage
Device temperature
Communication status
Measurement timestamp
Firmware and configuration version

The application platform may then display the result as pressure, tank level, water flow, temperature or another process variable.

Why Is 4–20 mA Widely Used?

The 4–20 mA current loop is a long-established industrial signaling method. Instead of representing a measurement as a digital register, the transmitter varies the current in the loop.

In a typical configuration:

4 mA represents the bottom of the configured measurement range.
20 mA represents the top of the configured measurement range.
Values between these points represent proportional measurements.

For example, if a pressure transmitter is configured for 0–10 bar:

4 mA corresponds to 0 bar.
12 mA corresponds approximately to 5 bar.
20 mA corresponds to 10 bar.

The exact conversion must use the transmitter’s documented measurement range. A converter should not assume that every connected instrument represents the same unit or scale.

Current-loop signaling is commonly selected for industrial sites because it can remain reliable across relatively long cables and electrically noisy environments. A LoRaWAN interface allows these field signals to become part of a remote IoT monitoring system.

Which Instruments Can Be Connected?

A LoRaWAN analog input device can work with many instruments that provide a compatible current-loop output.

Pressure Transmitters

Pressure monitoring applications may include:

Water pipelines
Irrigation systems
Pump stations
Compressed-air equipment
Hydraulic systems
Filter differential pressure
Industrial process lines
Building water systems

The platform can display pressure trends and issue alerts when readings move outside the configured operating range.

Level Transmitters

Hydrostatic probes and other level instruments commonly provide a 4–20 mA output.

A converter can transmit level data from:

Water tanks
Wells
Reservoirs
Wastewater chambers
Chemical tanks
Agricultural storage tanks
Industrial sumps

Unlike an integrated level sensor, the converter does not directly measure the liquid. It digitizes the output of the connected transmitter. The transmitter range, installation offset and tank conversion rules must be configured separately.

Flow Transmitters

Industrial flow instruments may output a current proportional to the measured flow rate.

Remote flow monitoring can support:

Water-distribution analysis
Irrigation management
Pump-performance checks
Process-water monitoring
Abnormal-consumption alarms
Industrial production records

If total consumption is required, the system may calculate it from successive flow measurements or use a separate pulse or digital totalizer input. The calculation method should match the application’s accuracy requirements.

Temperature Transmitters

Thermocouple, RTD and process-temperature transmitters can convert sensor measurements into a standard current-loop output.

A LoRaWAN converter can then transmit the temperature value without needing to support every thermocouple or RTD type directly.

Other Industrial Sensors

Additional compatible instruments may include:

Humidity transmitters
Water-quality analyzers
pH transmitters
Conductivity transmitters
Turbidity instruments
Position sensors
Load and force transmitters
Gas concentration transmitters
Wind and weather instruments
Vibration transmitters with analog output

Compatibility must be confirmed from the output specification, power requirements and wiring diagram of each instrument.

4-20mA Converter Versus RS485 Converter

Both products can connect existing industrial sensors to LoRaWAN, but they handle different signal types.

A 4–20 mA converter measures an analog current. It needs analog signal conditioning, an appropriate measurement circuit and calibration.

An RS485 converter exchanges digital messages with a sensor. It needs the correct baud rate, device address and Modbus register map or proprietary protocol.

A sensor with a 4–20 mA output does not provide Modbus registers. Similarly, an RS485 sensor cannot normally be connected directly to an analog current input.

Some OEM devices can combine analog, RS485, pulse and digital inputs, but each additional interface increases hardware, enclosure, firmware and validation requirements.

Passive Input or Loop-Powered Output?

This is one of the first questions to resolve in a custom project.

Passive Measurement Input

A passive analog input measures a current loop that is already powered by another supply.

The installation may contain:

A powered industrial transmitter
An existing control-panel supply
A PLC or process-control loop
A separate loop power source

The LoRaWAN converter measures the current without being responsible for powering the transmitter.

The circuit must be designed so that it does not introduce an unacceptable voltage drop or interfere with the existing control system.

Converter-Supplied Loop Power

Some projects require the LoRaWAN device to power a two-wire transmitter before taking a measurement.

The operating sequence may be:

Wake the converter.
Enable the transmitter supply.
Wait for the sensor to stabilize.
Measure the current.
apply filtering and scaling.
Send the result.
Turn off the sensor supply.
Return to sleep.

This arrangement can support remote battery or solar installations, but the power budget depends heavily on the transmitter’s voltage, current consumption and warm-up time.

The customer should provide the transmitter datasheet before the power architecture is selected.

Two-Wire, Three-Wire and Four-Wire Transmitters

A 4–20 mA output does not automatically reveal how the instrument is powered.

Two-Wire Transmitter

A two-wire transmitter receives power and sends the measurement through the same current loop. The power supply must provide sufficient voltage after accounting for cable loss and the voltage required by all loop components.

Three-Wire Transmitter

A three-wire instrument normally has separate supply and common connections plus a signal output. Its grounding and input topology must be checked carefully.

Four-Wire Transmitter

A four-wire device uses separate power and signal connections. It may be easier to integrate in some powered installations, but isolation and grounding requirements still need evaluation.

Incorrect wiring can produce inaccurate readings or damage equipment. A custom manufacturer should therefore request the transmitter’s wiring diagram rather than relying only on the phrase “4–20 mA output.”

Analog Front-End Design

The analog front end converts loop current into a voltage that the microcontroller or analog-to-digital converter can measure.

Important design factors include:

Input measurement range
Conversion resistance
ADC resolution
Reference-voltage stability
Component tolerance
Temperature drift
Input filtering
Common-mode conditions
Reverse-polarity protection
Surge and transient protection
Channel-to-channel isolation
Ground-loop risk
Calibration procedure

An increased ADC resolution does not automatically guarantee an accurate product. Overall accuracy depends on the complete signal path, reference source, PCB layout, temperature behavior and calibration method.

When Is Electrical Isolation Needed?

Industrial installations may contain different ground potentials, long cables, motors, pumps and electrical interference.

Isolation may be considered when:

The transmitter and converter use different power systems.
Long cables create ground-potential differences.
Several loops share one multi-channel converter.
The device is installed near noisy industrial machinery.
The existing loop is also connected to a PLC or controller.
The project requires stronger protection between field and logic circuits.

Isolation increases component cost, PCB area and power consumption. It should be selected from the actual electrical environment instead of added only as a marketing feature.

Detecting Input and Wiring Faults

A useful wireless converter should distinguish a genuine low process value from a wiring or instrument problem.

Depending on the transmitter and agreed diagnostic rules, firmware may identify:

Open loop
Current below the expected range
Current above the expected range
Unstable input
Sensor power failure
ADC saturation
Missing external supply
Channel disabled
Calibration error

The acceptable current limits should be configurable where different transmitter vendors use different fault-signaling behavior.

The platform should label invalid readings clearly rather than displaying them as normal process measurements.

Scaling Current Into Engineering Units

The converter or platform must translate measured current into a useful value.

The project needs the following information:

Minimum current
Maximum current
Minimum engineering value
Maximum engineering value
Unit
Decimal precision
Linear or nonlinear conversion
Sensor offset
Calibration correction

For a linear transmitter, the general conversion is:

Engineering Value = Minimum Value + Current Position × Measurement Span

Some sensors use a nonlinear response, lookup table or device-specific correction. These requirements should be documented in the payload and platform specification.

Local Filtering and Edge Processing

Industrial signals may fluctuate because of process turbulence, pump operation, electrical noise or sensor behavior.

Firmware can apply:

Multiple-sample averaging
Median filtering
Outlier rejection
Deadband reporting
Minimum-change thresholds
Alarm persistence
Hysteresis
Rate-of-change detection
Minimum and maximum recording
Periodic summaries

Filtering must be selected according to the process. Aggressive filtering may hide a real short-duration pressure event, while insufficient filtering may generate unnecessary alarms.

Edge processing can also reduce LoRaWAN traffic by transmitting meaningful changes and periodic summaries instead of every raw sample.

Measurement and Reporting Intervals

The measurement interval and LoRaWAN reporting interval do not need to be identical.

For example, the converter may:

Measure every few minutes.
Store the readings locally.
Transmit a summary at a longer interval.
Send an immediate packet when an alarm threshold is sustained.

The correct schedule depends on:

Process response time
Required alarm latency
Sensor warm-up period
Battery target
Network capacity
Local regulations
Historical-data requirements
Gateway availability

Safety-critical or fast closed-loop control should not depend only on an occasional LoRaWAN uplink. Local controls and appropriate industrial safety systems may still be required.

Power-Supply Options

An OEM LoRaWAN 4-20mA converter may use:

External DC power
Industrial 12 V or 24 V supply
Replaceable battery
Rechargeable battery
Solar power
A combination of external power and backup battery

An externally powered device can support more frequent sampling, multiple channels and lower-latency downlinks.

Battery operation requires a detailed analysis of:

Sensor excitation current
Sensor warm-up time
Analog measurement duration
LoRaWAN transmission interval
Spreading factor
Confirmed-message retries
Downlink frequency
Local storage
Operating temperature
Battery chemistry
Sleep current

Battery life should be calculated from the final operating profile and validated on prototypes. Nominal battery capacity alone is not sufficient.

LoRaWAN Payload Design

A compact uplink may include:

Device identifier
Channel number
Raw current value
Scaled engineering value
Unit or configuration reference
Alarm flags
Input fault state
Battery or supply voltage
Record sequence number
Timestamp or time offset
Firmware version
Configuration version

The payload specification should define:

Byte order
Field length
Scaling factor
Signed and unsigned values
Invalid-value representation
Alarm-bit assignments
Protocol version
Backward compatibility

A clear payload document allows the customer’s Network Server and application platform to decode data consistently.

Custom sensor drivers, analog processing, low-power control, payload encoding and remote configuration can be evaluated through Jinshengchang’s LoRaWAN firmware development service.

Gateway and Platform Integration

The converter transmits data to a LoRaWAN gateway. The gateway then forwards the packets through Ethernet, Wi-Fi or cellular backhaul.

Actual coverage depends on:

Gateway height
Antenna location
Building construction
Metal machinery
Tanks and enclosures
Terrain and vegetation
Device antenna design
Radio interference
Frequency plan
LoRaWAN data rate

A site survey and pilot deployment are more reliable than selecting gateway quantity from an advertised maximum distance.

The industrial LoRaWAN gateway selection guide provides additional considerations for planning private networks.

A monitoring platform may include:

Device registration
Channel configuration
Engineering-unit conversion
Current and historical values
Threshold alarms
Input-fault alarms
Battery and power status
Offline notifications
Multi-site dashboards
Data export
MQTT or HTTP integration
Customer APIs
User permissions
Configuration records

The buyer should specify whether data will be delivered to an existing platform, a private server or a new application.

OEM Hardware and Firmware Options

A custom product may be developed with:

One or multiple 4–20 mA inputs
0–10 V analog input
Pulse or dry-contact input
RS485 or Modbus interface
Isolated analog channels
Converter-supplied loop power
External DC input
Battery or solar operation
Local flash storage
Internal or external antenna
DIN-rail enclosure
Wall- or pole-mounted enclosure
Local display
Bluetooth or NFC configuration
Relay output
Customized connectors and cables
Customer payload protocol
Logo, label and packaging customization

The most effective design normally includes only the interfaces required by the target application.

Regional Frequency and Compliance Planning

The converter and gateway must be configured for the deployment country.

Common LoRaWAN regional plans include:

EU868
US915
AU915
AS923 variants
CN470
IN865
KR920
RU864

The destination market affects the channel plan, transmit-power settings and product compliance requirements. Certification and enclosure claims should only be made for the final tested production design.

Recommended OEM Development Process

1. Collect Transmitter Documentation

Provide output type, wiring diagram, measurement range, supply voltage, load requirements, warm-up time and sample instruments.

2. Define the Installation Architecture

Confirm whether the current loop is already powered, whether another controller is connected and whether isolation is required.

3. Specify the Data Requirements

Define units, measurement frequency, reporting interval, filtering, alarm rules and local storage.

4. Select Hardware

Choose the analog front end, ADC, MCU, LoRaWAN radio, power system, antenna, enclosure and protection circuits.

5. Develop Firmware and Payload

Implement measurement, calibration, scaling, fault detection, low-power control, LoRaWAN communication and server decoding.

6. Test Representative Instruments

Verify operation with actual transmitters across their measurement ranges, including abnormal inputs and power interruptions.

7. Conduct a Site Pilot

Evaluate radio coverage, electrical noise, readings, alarm behavior, power consumption and platform integration.

8. Prepare Production

Finalize calibration procedures, test fixtures, firmware versioning, device credentials, labels, packaging and traceability records.

Information Required for a Quotation

Customers should provide:

Sensor or transmitter brand and model
4–20 mA wiring diagram
Two-wire, three-wire or four-wire configuration
Measurement range and engineering unit
Number of analog channels
Existing loop-power arrangement
Required input isolation
Measurement and reporting intervals
Alarm and filtering requirements
Local storage requirement
Battery, solar or external power preference
Indoor or outdoor installation
Enclosure and mounting requirements
Destination country and frequency plan
Network Server and platform requirements
Prototype quantity
Estimated production quantity
Branding and packaging requirements

Providing sample transmitters can reduce compatibility risk during prototype testing.

Frequently Asked Questions

Can the converter work with every 4–20 mA sensor?

Not automatically. The transmitter’s wiring, supply voltage, load requirements, measurement range and grounding arrangement must be checked before connection.

Can a battery-powered converter also power the transmitter?

It can be designed to provide switched loop power, but feasibility depends on the transmitter voltage, warm-up time, current consumption and measurement schedule.

Can the device connect to an existing powered loop?

A passive measurement input can be developed for this purpose. Input loading, grounding and isolation must be evaluated so the converter does not interfere with the existing control system.

Can one converter read several transmitters?

A multi-channel design is possible. Channel count, isolation, power supply, enclosure size and sampling time must be defined during development.

Can it support both 4–20 mA and 0–10 V?

A combined analog-input product can be developed, but each signal type needs an appropriate input circuit, protection and calibration method.

What happens if the gateway goes offline?

The converter can continue measuring and store records locally if memory and recovery functions are included. Historical uploads should be paced after communication returns.

Is LoRaWAN suitable for real-time machine control?

LoRaWAN is well suited to telemetry, alarms and scheduled monitoring. Processes requiring deterministic, very fast or safety-critical control should use appropriate local control systems.

Can thresholds be changed remotely?

Remote configuration can be implemented through controlled downlinks or another service interface. Permissions, parameter validation and configuration-version tracking should be included.

Can the product use our own platform and brand?

Custom payloads, APIs, dashboards, labels, enclosure markings and packaging can be evaluated as part of an OEM or ODM project.

Conclusion

A LoRaWAN 4-20mA converter provides a practical way to connect existing industrial transmitters to remote monitoring systems without replacing proven field instruments.

Reliable performance depends on much more than reading the nominal current. The product must account for loop power, transmitter wiring, analog accuracy, isolation, fault detection, calibration, power consumption, LoRaWAN capacity and platform conversion.

Shenzhen Jinshengchang Technology Co., Ltd. can evaluate OEM and ODM projects covering analog hardware, embedded firmware, LoRaWAN communication, gateway deployment, payload protocols, APIs, prototypes and production preparation.

Request an OEM LoRaWAN 4-20mA Converter Proposal

Send your transmitter datasheet, wiring diagram, required channel count, power architecture, installation environment, destination country, expected quantity and platform interface for technical evaluation.

Shenzhen Jinshengchang Technology Co., Ltd.

WhatsApp: +86 134 8088 1974
Phone: +86 134 8088 1974
Phone: +86 177 2242 0256
Email: 397017470@qq.com