How to Test a 4-20mA Transmitter Using FNIRSI SG-004A Malaysia
How to Test a 4-20mA Transmitter Using FNIRSI SG-004A Malaysia
4-20mA transmitters are widely used in industrial automation, factory maintenance and process control systems.
These transmitters convert pressure, temperature, flow and level measurements into electrical signals for PLC and DCS controllers.
When incorrect readings occur, technicians need to identify whether the problem comes from the transmitter, wiring, power supply or PLC analog input.
The FNIRSI SG-004A Multifunction Signal Generator helps technicians perform signal simulation, measurement and troubleshooting.
What Is a 4-20mA Signal?
A 4-20mA signal is commonly used to transmit measurement data between industrial sensors and control systems.
For example, a pressure transmitter with a measurement range of 0-10 bar may produce the following signals.
Current OutputPressure4mA0 bar8mA2.5 bar12mA5 bar16mA7.5 bar20mA10 bar
If the transmitter produces 12mA, the PLC should display approximately 5 bar when correctly configured.
How to Check a 4-20mA Transmitter
Step 1: Check the Power Supply
Verify that the transmitter receives the correct operating voltage.
Step 2: Check the Wiring
Inspect the signal cables, terminals and electrical connections.
Step 3: Measure the Current Signal
Select the appropriate current measurement mode on the FNIRSI SG-004A.
Connect the instrument according to the manufacturer's instructions and the transmitter wiring configuration.
Step 4: Compare the Reading
Compare the measured current with the expected process value.
If the output differs significantly, further investigation may be required.
How to Simulate a 4-20mA Signal to a PLC
The FNIRSI SG-004A can generate known current signals for compatible PLC analog inputs.
Step 1: Confirm the PLC analog input supports 4-20mA.
Step 2: Identify the correct active or passive current configuration.
Step 3: Safely isolate the transmitter from the test circuit.
Step 4: Connect the SG-004A using the correct output mode and wiring arrangement.
Step 5: Generate 4mA, 12mA and 20mA signals.
Step 6: Check whether the PLC displays the expected values.
If the PLC responds correctly, technicians can continue investigating the transmitter and field wiring.
If the PLC displays incorrect values, check the PLC scaling, analog input configuration and signal connections.
Common 4-20mA Troubleshooting Problems
1. No Current Signal
Possible causes include missing power supply, damaged wiring or transmitter failure.
2. Unstable Signal
Possible causes include loose terminals, electrical interference or grounding problems.
3. Incorrect PLC Reading
Check transmitter scaling, PLC programming and analog input configuration.
4. PLC Reading Does Not Change
Investigate the analog input module, signal wiring and configuration settings.
FNIRSI SG-004A Main Applications
The FNIRSI SG-004A is useful for:
4-20mA Signal Simulation
PLC Analog Input Testing
Pressure Transmitter Troubleshooting
Temperature Transmitter Testing
Industrial Control Panel Commissioning
Factory Maintenance
Process Instrumentation
Industrial Automation Training
Its multifunction design allows technicians to perform different signal testing tasks using one portable instrument.
Who Should Use the FNIRSI SG-004A?
The SG-004A is suitable for:
Factory Maintenance Technicians
PLC Engineers
Instrumentation Technicians
Automation Contractors
Control Panel Manufacturers
Process Plant Maintenance Teams
Engineering Training Centres
It is particularly useful for troubleshooting industrial control systems that rely on analog signals.
Important: The SG-004A is intended for signal testing and troubleshooting. For applications requiring traceable calibration, use an appropriate calibrated reference instrument.
FNIRSI SG-004A Signal Generator Supplier Malaysia
MTM Precision Sdn Bhd supplies industrial testing and measuring instruments for factories, engineering companies and maintenance contractors throughout Malaysia.
For customers working with PLC systems, 4-20mA transmitters and industrial automation, the FNIRSI SG-004A offers a practical signal testing solution.
Customers can WhatsApp us a photo of their PLC module, transmitter or existing testing instrument for product selection assistance.
MTM Precision Sdn Bhd
Showroom & Service Centre
No. 29-1 & 2, Jalan Bandar 18,
Pusat Bandar Puchong,
47160 Puchong, Selangor, Malaysia.
Tel: 03-8080 7172
WhatsApp: +6016-660 7346
Email: mtmpre@yahoo.com
Website: www.mtmpre.com.my
We serve customers in Kuala Lumpur, Selangor, Johor, Penang, Melaka, Negeri Sembilan, Perak, Pahang, Kedah, Kelantan, Terengganu, Perlis, Sabah and Sarawak.
08 Oct 2026
