FAT procedure for PLC panel:


FAT (Factory Acceptance Test) is carried out for every instrument before the final installation, according to the standard IEC 61511. The FAT process involves testing the machinery during and after the assembly process by ensuring that it is designed and working according to design specifications.

FAT ensures the proper functioning of the components and controls according to the functionality of the equipment itself. As the name suggests, the factory performs this testing.

PLC FAT procedure:

As FAT is the final check carried out before the final installation the check should ensure the complete and proper working of the entire PLC system. The check includes all aspects of the PLC machine, such that:

  • Hardware
  • Software
  • Power supply
  • Earthing
  • Programming logics
  • Communication ports etc.,

Procedure for FAT inspection in a PLC as follows:

Visual Check:

The panel developed for this project is subject to visual review by the customer to ensure that all parts and accessories conform with the final approved panel specifications.


  • Visual inspection to confirm that all material is as per panel drawings.
  • Confirm that all components and accessories are mounted as per panel drawings.

Appearance and construction:

The appearance & construction check is to review the panel drawing and other construction documents on the basis of which the inspection is conducted. The check ensures the panel is constructed as per the design.


  • The purpose of this test is to ensure that panels are free from scratches and deformities

  • Check that the ‘construction’ sketches were drawn based on the accepted drawings distributed at the time of the call for an inspection.

  • Check that the modifications carried out by the’ Construction’ drawings are marked in blue pen and the engineer-in-charge is dated and signed.

  • Check that the changes made in the sketches have no effect on the model.

Panel Earthing:

Earthing of the PLC panel should be checked and verified for proper earthing which ensures the safety of the personals working on the PLC panel and from other electrical hazardous situations.


  • Check that the earth point of the board is on the earth of the building.
  • Test that 0V is attached to the earth bar inside the board.
  • Check that the base of the panel is attached to the earth ring.

Power supply check:

Power supply to the PLC and the supply generated inside the panel is crossed checked with reference of power supply data sheet.


  • Measure the volatge of incoming power supply

  • Measure the voltage generated inside the PLC panel as per approved data sheet and approved wiring diagram no.

Panel Wiring check:

Panel wiring is subjected to visual and functional inspection to confirm the wiring done with the terminal assessment, panel drawings and wire colors as per the drawing.


  • Visually and functionally test that each panel wiring is in order on the basis of the above objectives.

  • Check the color code of the drawing is as per approved drawing.

PLC I/O architecture:

To verify the PLC architecture with reference to the approved PLC System Architecture drawing.


  • Test visually that processors and I / Os are linked to EHTERNET Bus according to the approved system architecture.

  • Visually check the availability of the Ethernet port that is used for programming & SCADA to connect to the Ethernet network.

PLC start-up:

PLC goes to normal power up operation, as long as all application software is stored in the respective PLCs.


  • Power on the entire system
  • Power off the PLC
  • Power on the PLC again

I/O functional check:

Digital input check:

Check whether all Digital Inputs should be terminated at the proper terminal only.


  • Attach jumper to the termination block of the digital output field as shown in the cable diagrams to toggle field data.
  • Observe the PLC input module LED warning.
  • Observe the correct status on the programming terminal in the PLC memory.

Digital output check:

Check whether all Digital outputs should be terminated at the proper terminal only.


  • Force the Output with the help of programming software.
  • In the corresponding digital output termination module observe the LED indication.
  • Check Relay Operation and check for specific output contacts assigned.
  • Observe the correct scada display command.

Analog input:

All analog inputs should only be terminated at the right terminal


  • Measure the current with a multimeter given by the origin
  • Observe the corresponding value on the SCADA display

Analog output:

All analog output should only be terminated at the right terminal

  • Force the Output memory location with the help of programming software.
  • Observe corresponding value on SCADA screen.

PLC Programming port:

The programming terminal is controlled via the programming port of the PLC.


  • Connect the programming terminal to the programming port of the PLC.
  • Apply logic while running the processor.
  • Delete logic at the end of the test

PLC communication port:

This test is intended to check that the Ethernet communication ports are working. The programming terminal is connected to the PLC through all the connection points available: Ethernet.


  • Link the programming terminal to all links and laptops accessible.
  • Test the connection of the programming terminal to the PLC CPU.

CPU/IO network redundancy check::

The aim of this test is to check the redundancy of the CPUs and network.


  • To switch off the Primary PLC and see whether the network switches to secondary PLC.

MMI check:

The aim of these tests is to verify that the displays, security feature, data archiving, alarms, trends and reporting are generated as requested by the customer.


  • Check SCADA screens
  • Check security feature
  • Check Alarm history
  • Check trending

Trip/Interlock logic check:

This experiment is intended to verify that the console controls the PLC system.


  • Force any fault condition and check for the trip/interlock fucntioning

Online system configuration check:

The aim of this test is to confirm that the online system configuration is correct.


  • Check all available ports for communication.
  • Check logic is performing according to the change.

Program logic testing:

The object of this test is to verify the functional logic of the electronic interlocks.


  • Force the inputs and the required interlocks are checked

PLC FAT checklist:

Panel-Check-List.pdf (88.1 KB)