DCS and PLC Site Acceptance Test (SAT)

Site acceptance test is test to verify the Automation system like DCS (Distributed Control System) & Subsystems are well connected & communicate with each other without having any Hardware or software failure.

SAT activity requires involvement of MAC Contractor, EPC Contractor, Subsystem Vendor.

MAC (Main Automation Contractor i.e., Honeywell, Yokogawa etc.) should prepare SAT procedure & submit to PMT (Project Management Team) for approval during CDR (Critical Design Review).

DCS (Distributed Control System) SAT also includes Integration Test with various Sub System or Package PLC (programmable logic Controllers)

EPC (Engineering Procurement Construction) Contractor coordinates & manages Integration Test activity with sub system vendors.

EPC ensures DCS is ready for SAT

Like ensuring all Eng/HIS( DCS Engineering Stations), all HIS(Human Interface Station), All DCS System Cabinets(Processor Cabinets), Marshalling Cabinates(Input Output Cabinets), All Network Cabinets, OPC (Object Embedding & Linking for Process Control) Servers, ALMS(Alarm Management) servers, PRM Servers(Plant Resource Manager), UGS(Unified Gateway System) for ENMCS, Printer, Installation of DCS real time redundant bus network, Installation of PIN Plant Information Network as per design, Consoles are ready.

Site Acceptance Test (SAT)

Site Acceptance Test consists of four main parts

  1. Inspection & testing of DCS Hardware

  2. Testing of DCS application software

  3. Inspection & testing of DCS marshalling cabinets & consoles

  4. Integration test with various package PLC systems.

Inspection & testing of DCS Hardware

DCS Hardware Check

It is to verify DCS components are healthy, installed & connected.


Using BOM (Bill of Material) & System Architecture drawing

  1. Verify all hardware system components are installed as per the System Architecture drawing.

  2. Ensure all DCS stations are connected (check ethernet/Fiber Optic cables) to system network like VNET/IP for Yokogawa DCS

  3. Open “System Status Display” in HIS, verify all DCS stations shown are healthy

  4. Disconnect ethernet cable, check System Status Display, reconnect & check its healthy again or not. When disconnected it should show cable status in Red, after reconnecting it should turn green again.

  5. Ping IP address of any DCS station it should reply.

Power & Grounding Check

It is to verify system & marshalling cabinets are getting Correct Power Supply & to verify AC safety & Instrument Circuit ground are connected properly & separately.

Procedure 1

Using Grounding Scheme drawing, PDP (power distribution Panel) GA Drawing & Wiring diagram

  1. Check AC voltage using multimeter at incomer terminals & at each component that uses AC power.

  2. Verify Grounding of DCS components to Instrument ground.

Procedure 2

Check DC voltage at output terminals of each 24VDC power supply, inside each PD panels & remote cabinets using multimeter. It should be 28VDC at output terminal of 24VDC power supply.

Verify cable connectivity between PDP & corresponding marshalling cabinet & ground bars.

DCS System Cable Check

It is to ensure all system cables are connected as per System Cable Schedule.

Procedure: Visually check all DCS system cables are connected as per System Cable Schedule,

Visually check all system cable grounding wires are connected to IO Card at Processor side

DCS System Inspection

System Start up

Each component of the system normally goes to operating environment automatically on power up, if all application software are installed. This activity makes sure all components automatically boot up.


Power off system components individually or all together. For Control Processor(FCS/CP) Turn off MCBs one at a time. For server cabinet installed PC’s, disconnect fuses related to station to be tested.

All system components must automatically boot up to its operating environment.

System Hardware Check

To ensure all system hardware are healthy & to ensure it generates alarm in case of any hardware failure.


Open “System Status Display” in HIS(Human Interface System) PC & check all Hardwares are shown healthy, Switch off an individual FCS/CP & verify if alarm is generated in HIS. Power it ON and check status goes Normal.

System Loading & Resource Check

This activity is to check total load on individual FCS/CPs & to check usage of function blocks in each FCS/CPs

FCS/CP Loading: Open “System status Display”, select properties of each FCS/CPs to monitor CPU idle time,

Resource Information check: Open “System View” in engineering station, select FCS → Resource Information to check use of Function Blocks in each FCS. It ensures availability of spare function blocks.

Printer check

To verify Printer is connected to the network and process alarm / system alarm, screen print, trends can be printed.


Check printer configuration for each HIS, verify if printer is Online or not, Simulate alarm & give print command. Printer should work without any problem.

DCS system, Marshalling, Network & Server cabinet inspection

Appearance & construction Check

Use Cabinet GA & Wiring Drawings to verify if the cabinets are free from Scratches, deformities or damage caused during packing, shipment or power up.

All components must have been mounted as per drawings & free from damages.

IO Check

AI (Analog Input) signals

Simulate 4-20 mA from marshalling cabinet & check the reading on particular Instrument’s faceplate on DCS. Feed 0,25%,50%,75%,100% also check Open Circuit condition.

AO(Analog Output) Signals

Put the closed Loop on DCS in Manual and feed 0,25%, 50%, 75%, 100% values, verify the 4-20 mA output on Marshalling cabinet.

DI (Digital Input) Signals

In marshalling cabinet short the corresponding DI signal & verify the status on DCS.

DO (digital Output) Signals

Force an instrument from DCS, check corresponding relay on marshalling cabinet got energized or not.

FF( Foundation Fieldbus) Signals

Select a sample segment from each FF module, connect FF transmitter on Segment, open corresponding Tag no on Operator Console, it should be healthy, check if status changes in case of connection failure by disconnecting the transmitter.

AI accuracy should be 0.25% of full scale & AO accuracy should be 1% of full scale.

Operator Station Check

Graphics check

All Plant Graphics punches raised during FAT (Factory Acceptance Test) punches should have been fixed. Requirement FAT Punch list, Configuration & Graphics Guidelines.


Open graphics windows & verify FAT punches have been cleared.

Trend Group Window Check

No. of trend points can be displayed together, Process Variable, Set point, Output etc.

Procedure: FAT punches should have been cleared.

FCS/CP (Field Control Station/ Control Processors) Application Inspection

Application inspection of FCS must include, simple loops, complex control loops, Calculations, sequence control, alarm messages, etc. Simulate I/O using software tool “Test Function” in DCS Engineering station.

This test is to be done only on FAT punches.

Documents required:

FAT Punchlist, P&ID, Control Narrative, Configuration & Graphics guidelines.


Simulate I/O to check loop function, calculation, sequence function etc. which are mentioned in FAT punch list.

Console & Desk inspection

Console & desk are supplied by Main Automation Contractor.


Visually verify Console bays are free from scratches & deformation using Console layout drawings & dimensional outline drawings.

PIN (Plant Information Network) Connectivity

PIN connects ESD, VMS, CCS, ALMS, OPC server & NTP Server

Procedure: Using System Architecture Drawing


  1. All PIN cables are connected, check connection status on switch.

  2. Check if all PIN stations are shown in network status.

3 Disconnect Ethernet cable from any PIN station, Reconnect the cable & confirm its status on network.

  1. Go to one of PIN station in command prompt PING other station IP address, PIN station pinged must reply.


VMS (Vibration Monitoring System)/MMS (Machine Monitoring System)

Communication between VMS & DCS is made using Modbus RTU protocol via RS485 serial cable.


  1. Connect Subsystem & verify communication with DCS using mapping list.

  2. Check DCS System Alarm, IO Card status

  3. Test Communication & verify closure of Open IFAT punches.

CCS (Compressor Control System)

Communication between VMS & DCS is made using Modbus RTU protocol via RS485 serial cable.


  1. Connect Subsystem & verify communication with DCS using mapping list.

  2. Check DCS System Alarm, IO Card status

  3. Test Communication & verify closure of Open IFAT punches.

ALMS (Alarm Management System) Test

ALMS Server Function Test

The test is to confirm AAM software provides Master Database for alarms, applies user defined alarm settings, captures & stores Alarms & Events, Generates Statistical Reports, KPI reports on alarms on events.

DAHS (Data Acquisition & Historization System) Connectivity Test

DAHS System Connectivity Test

DAHS Server stores historical data of DCS for upto 1 year.


  1. Open Command prompt from DAHS server & Ping OPC Server, verify if response received, do same in opposite way.

  2. Ping again with “Ping -t” command to target server for 30 seconds to check any network disturbance.

DAHS (Data Acquisition & Historization System) Data Collection Test

This test is conducted to verify that data collected by DAHS server is as per requirement for eg alarm should be generated once High, High High, Low, Low Low values are detected & it should go away after crossing deadband.


Check Instrument tag no. found on DAHS, verify its alarm & dead band matches as per DAHS records.