Omron SYSMAC C200HS Operation Manual page 142

Bit Control Instructions
Precautions
Example 1:
When There is No
Differentiated Instruction
00000
00000
22500
Example 2:
Simplifying Programming
00000
22500
00001 00002 00003
00004 00005
132
DIFU(13) and DIFD(14) operation can be uncertain when the instructions are
programmed between IL and ILC, between JMP and JME, or in subroutines. Re-
fer to 5-10 INTERLOCK and INTERLOCK CLEAR – IL(02) and ILC(03), 5-11
JUMP and JUMP END – JMP(04) and JME(05), and 5-23 Subroutines and Inter-
rupt Control for details.
In diagram A, below, whenever CMP(20) is executed with an ON execution con-
dition it will compare the contents of the two operand words (HR 10 and DM
0000) and set the arithmetic flags (GR, EQ, and LE) accordingly. If the execution
condition remains ON, flag status may be changed each cycle if the content of
one or both operands change. Diagram B, however, is an example of how
DIFU(13) can be used to ensure that CMP(20) is executed only once each time
the desired execution condition goes ON.
Diagram A
Diagram B
Although a differentiated form of MOV(21) is available, the following diagram
would be very complicated to draw using it because only one of the conditions
determining the execution condition for MOV(21) requires differentiated treat-
ment.
Address Instruction
CMP(20)
00000 LD
HR 10
00001 CMP(20)
DM 0000
DIFU(13) 22500
Address Instruction
00000 LD
CMP(20)
00001 DIFU(13)
HR 10
00002 LD
DM 0000 00003 CMP(20)
Address Instruction
DIFU(13) 22500
00000 LD
00001 DIFU(13)
MOV(21) 00002 LD
00003 LD
HR 10
00004 AND NOT
DM 0000
00005 AND NOT
00006 OR LD
00007 LD
00008 AND NOT
00009 OR LD
00010 MOV(21)
Section 5-9
Operands
00000
HR 10
DM 0000
Operands
00000
22500
22500
HR 10
DM 0000
Operands
00000
22500
22500
00001
00002
00003
---
00004
00005
---
HR 10
DM 0000