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

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 t...

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 :-

Bit Logic Instruction in Simatic manager

There are total 14 instructions under the bit logic instruction like NO contact, NC contact, SR flip-flop, RS flip-flop,invert power flow etc. lets see the detailed use of them. A) Normally open contact :- Normally open contacts are closed when the bit value stored at the specific address is equal to 1 (one)(here the specific address refers to the address assigned to the NO contact), when we press the Normally open contact assigned to the specific address then it becomes functionally closed and we get supply. here in below fig. when we press the NO contact I0.0 then Output Q0.0 gets ON and when we release the input I0.0 then Output gets OFF. B)Normally Closed Contact :- Normally closed contacts are closed when the bit value stored at the specific add, i.e. the address assigned to the NC contact is equal to 0(zero). when we press the Normally closed contact assigned to the specific address then it becomes functionally open and supply is cuts off. NC contact wor...

blog2code

Search This Blog