FNIRSI SG-003A for System Integrator and Control Panel Testing Malaysia
FNIRSI SG-003A for System Integrator and Control Panel Testing Malaysia
For a system integrator or control panel builder, waiting until every field transmitter is installed before testing PLC analog inputs can slow down a project.
The PLC panel may already be completed.
The HMI program may already be loaded.
But the pressure transmitter, flow transmitter, level transmitter or temperature transmitter may still be at site.
How can you test the control system before all field instruments are available?
For suitable applications, a portable signal generator such as the FNIRSI SG-003A can provide known signals for PLC analog input testing, HMI checking, scaling verification and commissioning work.
This can be particularly useful for automation companies and panel builders in Malaysia.
Why System Integrators Need Signal Simulation
A typical industrial automation system may include:
Field Transmitter > 4-20 mA > PLC > HMI > Alarm / Control Logic
During panel fabrication, the field transmitter may not yet be connected.
But much of the remaining system can still be checked.
A known test signal allows the engineer to simulate a suitable field input and observe what happens inside the PLC and HMI.
Application 1: Test PLC Analog Inputs Before Site Installation
Imagine a new control panel has:
8 analog input channels
The field instruments will eventually include:
2 pressure transmitters
2 flow transmitters
2 level transmitters
2 temperature transmitters
The panel builder does not necessarily need to wait for all eight transmitters before performing basic PLC input checks.
For compatible inputs, known signals can be introduced according to the approved test procedure.
Example: 0-10 Bar Pressure Input
The PLC is programmed for:
4-20 mA = 0-10 bar
Expected values are:
4 mA = 0 bar
8 mA = 2.5 bar
12 mA = 5 bar
16 mA = 7.5 bar
20 mA = 10 bar
By checking several points, the engineer can verify whether the PLC and HMI respond according to the intended scaling.
Application 2: Check HMI Engineering Values
A PLC input may be functioning correctly while the HMI displays the wrong value.
For example:
Test input:
12 mA
PLC engineering value:
5 bar
HMI display:
50 bar
This suggests that the problem may be related to:
HMI scaling
Decimal position
Wrong tag
Unit conversion
Software calculation
A known input gives the engineer a fixed reference point for troubleshooting.
Application 3: Check Tag Assignment
Large control panels can contain many analog channels.
During wiring or programming, channels may be assigned incorrectly.
For example:
Pressure Transmitter 1 should be connected to AI01
but the HMI tag is linked to AI02.
By applying a known signal to one channel at a time, the engineer can verify that the correct PLC and HMI tags respond.
This is useful during FAT, commissioning and troubleshooting.
Application 4: Verify PLC Scaling
Scaling errors are common during new projects.
Suppose the field transmitter will be:
0-16 bar = 4-20 mA
But the PLC programmer accidentally configures:
0-10 bar = 4-20 mA
At:
12 mA
the correct pressure for the intended 0-16 bar range should be:
8 bar
If the HMI shows:
5 bar
the engineer immediately knows that the engineering range requires investigation.
Application 5: Test Alarm Thresholds
Suppose a pressure system has:
Low Pressure Alarm = 2 bar
High Pressure Alarm = 8 bar
A system integrator may need to verify that the alarms operate at the intended points.
Known signal testing can help check whether:
Alarm indication appears
HMI colour changes
Alarm message is correct
PLC alarm bit activates
Alarm reset works
However, testing must be performed under controlled conditions because the same signal may also influence real outputs or interlocks.
Application 6: Check Interlock Logic
Analog values may be used for more than display.
For example:
Low tank level > Stop pump
High pressure > Stop compressor
High temperature > Activate alarm
Low flow > Stop process
During commissioning, an engineer may need to verify whether these functions respond correctly.
A known input can support this type of functional testing.
But the engineer must understand what equipment may operate when the signal changes.
Application 7: Factory Acceptance Test
During a Factory Acceptance Test, customers may want to see how the control panel responds to simulated field conditions.
For example:
0%
25%
50%
75%
100%
For a standard linear 4-20 mA input, these correspond to:
4 mA
8 mA
12 mA
16 mA
20 mA
This provides a simple method for demonstrating suitable analog input functionality before the panel is delivered to site.
Application 8: Site Acceptance Test
After installation, the same concept can support Site Acceptance Test activities.
The engineer can verify the signal path from the appropriate test point through:
Field Wiring > Control Panel > PLC > HMI
Depending on the test procedure, this can help identify:
Wiring errors
Wrong terminals
Wrong channels
Incorrect scaling
HMI tag errors
Software problems
Application 9: Commissioning Before the Process Is Running
A common commissioning problem is that the control system is ready but the process is not.
For example:
The water tank is empty.
The pump cannot run yet.
The production line has not started.
The pressure system is not pressurised.
But the automation engineer still needs to test the PLC program.
A suitable signal generator allows parts of the control system to be checked without requiring the actual process to reach every test condition.
Application 10: Troubleshoot a Completed Panel
A panel has already been commissioned, but one analog channel suddenly shows an incorrect value.
The engineer needs to determine whether the problem comes from:
Field transmitter
Field wiring
PLC analog input
Scaling
HMI
Known-signal testing can help divide the system into sections.
If the PLC responds correctly to a known signal, the investigation can move towards the field side.
Why 5-Point Testing Is Useful
Testing only:
4 mA
and
20 mA
confirms the endpoints.
For a more complete functional check, engineers may also test:
8 mA
12 mA
16 mA
For a linear 0-100% system:
4 mA = 0%
8 mA = 25%
12 mA = 50%
16 mA = 75%
20 mA = 100%
Intermediate points can reveal scaling or software problems that endpoint-only testing may miss.
Example: Tank Level Control Panel
Suppose the system is designed for:
0-5 m = 4-20 mA
Expected PLC values are:
4 mA = 0 m
8 mA = 1.25 m
12 mA = 2.5 m
16 mA = 3.75 m
20 mA = 5 m
The system integrator can check:
PLC raw input
Engineering value
HMI level
Low-level alarm
High-level alarm
Pump logic
This creates a more complete commissioning test than simply checking whether the HMI displays a number.
Example: Temperature Monitoring Panel
A temperature transmitter will eventually provide:
0-100掳C = 4-20 mA
Before the transmitter is installed, the engineer may check the receiving system at:
4 mA = 0掳C
12 mA = 50掳C
20 mA = 100掳C
This can help verify the PLC and HMI side.
It does not physically simulate the temperature process itself.
Signal Simulation vs Sensor Simulation
This distinction is important.
A 4-20 mA signal generator simulates an electrical process signal for compatible equipment.
It does not automatically simulate every sensor type.
For example:
Pt100
RTD
Thermocouple
and other sensor inputs may require different simulation functions or equipment.
Always identify the actual input type before connecting a signal generator.
FNIRSI SG-003A for Panel Builders
For suitable applications, the FNIRSI SG-003A can be considered for:
PLC analog input testing
Control-panel testing
FAT
SAT
Commissioning
HMI checking
Scaling verification
Loop checking
Troubleshooting
This makes the product particularly relevant to automation companies, system integrators and control-panel builders.
Do You Still Need a Multimeter?
Yes.
A signal generator does not make a multimeter unnecessary.
A multimeter helps technicians check existing electrical conditions.
A signal generator helps provide a known test condition.
For commissioning work, these functions complement each other.
Is a Signal Generator Enough for Formal Calibration?
Not necessarily.
Panel commissioning and functional testing are different from formal calibration.
Calibration work may require:
Higher accuracy
Traceability
Reference standards
Measurement uncertainty
Documented procedures
Calibration certificates
Select the instrument according to the project requirement.
Useful Tool for Automation Companies
A system integrator may work on different projects every month:
Water treatment
Factory automation
HVAC
Pump systems
Boiler controls
Process plants
Building services
Production machinery
A portable signal generator can therefore be useful across many projects rather than being tied to one specific machine.
Before Going to Site
For commissioning work, it is useful to review:
PLC model
Analog input module
Signal type
Transmitter range
Wiring diagram
I/O list
PLC scaling
Alarm setpoints
This allows the engineer to prepare suitable test points before arriving at site.
Important Safety Reminder
Before applying a test signal:
Review the wiring diagram
Confirm the input type
Check the permitted signal range
Identify the correct terminals
Confirm polarity
Understand the loop power arrangement
Check PLC and HMI logic
Determine what outputs may respond
Follow project and site safety procedures
A simulated analog input may activate:
Pumps
Valves
Motors
Fans
Alarms
Interlocks
Automatic sequences
During FAT or commissioning, outputs may need to be safely isolated or controlled according to the approved procedure.
Looking for FNIRSI SG-003A in Malaysia?
MTM Precision Sdn Bhd supplies the FNIRSI SG-003A Signal Generator in Malaysia for system integrators, automation engineers, control-panel builders and industrial maintenance teams.
If you are building a PLC panel and are unsure whether the SG-003A is suitable for your analog input testing, send us a photo of the PLC analog input module, transmitter specification, I/O list or wiring diagram through WhatsApp.
We can help evaluate the application before you purchase.
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
Serving customers across Selangor, Kuala Lumpur, Johor, Penang, Melaka, Negeri Sembilan, Perak, Pahang, Kelantan, Terengganu, Kedah, Perlis, Sabah and Sarawak.
04 Oct 2026
