I/O Instruction Timing - Omron SYSMAC CS/CJ Series Programming Manual

Basic Concepts
2-1-9

I/O Instruction Timing

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Differentiated Instructions
36
FERENTIATE
differentiation UP and DOWN instructions as well as upwardly/
downwardly differentiated LOAD instructions (@LD/%LD).
• Input Instructions (Logical Starts and Intermediate Instructions): The
instruction reads bit status, makes comparisons, tests bits, or perform
other types of processing every cycle and will output an OFF execution
condition (power flow stops) when results switch from ON to OFF. The
execution condition will turn ON the next cycle.
Downwardly differentiated input instruction
The following timing chart shows different operating timing for individual
instructions using a program comprised of only LD and OUT instructions.
B1
Input
read
Input
B2
read
B3
Input
B4
read
Input
B5
read
B6
Input
B7
read
!
Input
B8
read
!
B9
!
B10
!
B11
!
B12
!
CPU pro-
cessing
Instruction I/O refresh
executed.
• A differentiated instruction has an internal flag that tells whether the previ-
ous value is ON or OFF. At the start of operation, the previous value flags
for upwardly differentiated instruction (DIFU and @ instructions) are set to
ON and the previous value flags for downwardly differentiated instructions
DOWN (DIFD) instructions,
Example
0001
03
OFF execution condition created for one
cycle only when CIO 00103 goes from
ON to OFF.
Input
read
Input
read
Input
read
Input
read
Input read
Input
read
Section 2-1
power flow