Answer / vicki

scan time is the time taken by DCS/PLC to read inputs,
execute program and as per input/logic update outputs
accordingly. PLC scan time depends on no. of inputs,
outputs and program size(total memory used, heap size). so
it may be different for different program(PLC). less scan
time means faster PLC action. scan time is mostly in mili
seconds, from 2ms onwords.

Answer / mohamed yousuf

scan time means the time required to read the
inputs,execute the program and generate the output this is
called scan time the scan time is usually in milli seconds
to nano seconds

Answer / amit patel

SCAN time of DCS /PLC defines as execution of one cycle of
program (reads the inputs, executed whole program and
writes output)

Normaly DCS scan time are 200msec ,500msec,1 sec
PLC scan time are less than 100msec.

Answer / purushotham

scan time , name it self indicates time required to scan the process of operation.
time taken to finish operation (reading inputs,logic(process) and execution (output) of results).

Answer / hiteshhp

Scan time is the time required to scan the inputs,program written and display the output accordingly.

As scan time of PLC is smaller than that of DCS,we use PLCs for faster operations in Industries.
Normally,PLC are used for Safety Purpose,the switches in interlocks for tripping,etc

Answer / sivabalan

PLC/DCS

Scan time is scan input and update input table, then perform logic and update logic table and finally update physical output devices. Taking time to execute above process is called.

Process

Scan input, Perform logic, Update output and finally perform house keeping task such as update the display.

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Hello friends i need check lists of different instruments during the Erection and commissioning in thermal power plant.Please help me.My Mail id is naba02222@gmail.com/naba02222@rediffmail.com Thanks Nabakishore Biswal

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