Omron SYSMAC mini SP10 Operation Manual page 85

Instruction Set
Flags
Precautions
Example 1: One-time
Execution of Other
Instructions
0000
0000
0215
Example 2: Use to Simplify
Programming
0000
0215
0001 0002 0003
0004 0005
Whenever executed, DIFD(11) compares its current execution with the pre-
vious execution condition. If the previous execution condition is ON and the
current one is OFF, DIFD(11) will turn ON the designated bit. If the previous
execution condition was OFF and the current execution condition is either
ON or OFF, DIFD(11) will either turn the designated bit OFF or leave it OFF.
The designated bit will thus never be ON for longer than one scan, assuming
it is executed each scan (see Precautions, below).
There are no flags affected by these instructions.
DIFU(10) and DIFD(11) operation can be uncertain when the instructions are
programmed between IL and ILC. Refer to 3-7-10 INTERLOCK and INTER-
LOCK CLEAR - IL(02) and ILC(03) for details.
In diagram A, below, whenever CMP(32) is executed with an ON execution
condition it will compare the contents of the two operand words (DR 10 and
DR 00) and set the arithmetic flags (GR, EQ, and LE) accordingly. If the ex-
ecution condition remains ON, flag status may be changed each scan if the
content of one or both operands change. Diagram B, however, is an example
of how DIFU(10) can be used to ensure that CMP(32) is executed only once
each time the desired execution condition goes ON.
Diagram A
Diagram B
The following diagram would be very complicated to draw without using
DIFU(10) because only one of the conditions determining the execution con-
dition for MOV(30) requires differentiated treatment.
Address Instruction
CMP(32)
000
DR 10
001
DR 00
DIFU(10) 0215
Address Instruction
000
CMP(32)
001
DR 10
002
DR 00 003
Address Instruction
DIFU(10) 0215
000
001
MOV(30) 002
003
DR 10
004
DR 00
005
006
007
008
009
010
Section 3-7
Operands
LD 0000
CMP(32)
DR
DR
Operands
LD 0000
DIFU(10) 0215
LD 0215
CMP(32)
DR
DR
Operands
LD 0000
DIFU(10) 0215
LD 0215
LD 0001
AND NOT 0002
AND NOT 0003
OR LD
LD 0004
AND NOT 0005
OR LD
MOV(30)
DR
DR
10
00
10
00
---
---
10
00
77