Important Definition In PLC :- SCAN TIME & SCAN CYCLE

SCAN TIME :-

Scan Time is nothing but the time taken by the processor to sense first input of the program and execute last output of the program.
The unit of Scan Time is Bits/Sec.

SCAN TIME depends on :-

no. of I/O's.(scan time ∝ no. of I/O's)
Length of Program.(scan time ∝ Length of program)
Speed of Process.(scan time ∝1/speed of process)

scan time is directly proportional to the no of I/O's, if program has more no of I/O's then it take relatively more time.
scan time is directly proportional to the length of program, more the length processor will take more time to execute the program.
and finally scan time is inversely proportional to the speed of the processor, more the speed less it will take time to execute the program.

SCAN CYCLE :-

"SCAN CYCLE is the cycle of Input Updation, Program Execution, & Output Updation of one Input and it's Output."

below fig shows the graphical representation of Scan Cycle :-
⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨⧨

Scan cycle.

Comments

Q1. Lamp should glow when start switch S1 is made ON. lamp should go off after 15 sec automatically. lamp should go OFF immediately when start switch S1 is made OFF. Lamp should go OFF immediately also when reset switch S2 is made ON even before the expiry of 15 sec time.

Timers in Siemens PLC Simatic manager

Timer :- Timer is nothing but a specialized clock in a programming software used to count the preset time intervals. In Siemens PLC we have various ty pes of timers as :- 1) S_PULSE(Pulse timer), 2) S_PEXT(Extended Pulse Timer), 3) S_ODT(On Delay Timer), 4) S_ODTS(Retentive On Delay Timer), 5) S_OFFDT(Off Delay Timer). You must find out another five instruction sets in Timer Block in Simatic Manager STEP 7 as :- -(SP) pulse timer coil, -(SE) extended pulse timer coil, -(SD) on delay timer coil, -(SS) retentive on delay timer coil, -(SF) off delay timer coil. 1) S_PULSE(Pulse timer) :- S_PULSE Timer Above Fig Shows how to use this timer in programming software,in this fig i have used 5 sec as a preset value, If you want to change it replace the 5 with any duration you want in S5T# 5 S. In S_PULSE timer if input to timer is ON then timer starts Counting time as well as we get the Output at the instant the input is made ON. In this timer if we mad

HOW TO DOWNLOAD AND INSTALL WONDERWARE FOR WINDOWS 8,7,10.

##You can Download a ZIP file of the software From Below link. https://drive.google.com/file/d/159y8W0c_bw0vvf1DNDQ08_QsLZ9h2Tb1/view?usp=sharing 1 ) You Can Also Watch a Video Tutorial of it below. 2) You can also read out steps from below :-

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