What is the Scan time of PLC?
- The Scan time can be defined as to the time taken by PLC to read input from sensor or devices, execute
and run the program and give output in one cycle.
PLC scan time depends on the following points
1.
Input scan
2.
Program scan
3.
Output scan
- Input scan: Input terminal of PLC reads all inputs which are coming from sensor or devices, create input image table
- Program Scan: Read input table and apply on input statue table according to the user program and create an output image table
- Output scan: read output image table and provide 0 or 1 logic on the output device
·
SCAN
CYCLE OF CPU:-
- · The Scan cycle depends on to no of inputs.
- · More input more scan time.
- · Application decides the scan time of PLC.
- · Scan time is normal Application is 1ms To 3 ms.
- · The speed of the processor module
- · The length of the ladder program
- · The type of instructions executed
- The actual ladder true/false conditions
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