Omron CPM1 - PROGRAMING MANUAL 02-2001 Programming Manual page 375

Work Bits (Internal Relays)
Work Bit Applications
Reducing Complex
Conditions
00000 00001
00002
00003
21600 00004
21600
00004
21600
00006
00007
Examples given later in this subsection show two of the most common ways to
employ work bits. These should act as a guide to the almost limitless number of
ways in which the work bits can be used. Whenever difficulties arise in program-
ming a control action, consideration should be given to work bits and how they
might be used to simplify programming.
Work bits are often used with the OUTPUT, OUTPUT NOT, DIFFERENTIATE
UP, DIFFERENTIATE DOWN, and KEEP instructions. The work bit is used first
as the operand for one of these instructions so that later it can be used as a
condition that will determine how other instructions will be executed. Work bits
can also be used with other instructions, e.g., with the SHIFT REGISTER
instruction (SFT(10)). An example of the use of work words and bits with the
SHIFT REGISTER instruction is provided in 7-16-1 SHIFT REGISTER –
SFT(10).
Although they are not always specifically referred to as work bits, many of the
bits used in the examples in Section 7 Instruction Set use work bits. Understand-
ing the use of these bits is essential to effective programming.
Work bits can be used to simplify programming when a certain combination of
conditions is repeatedly used in combination with other conditions. In the follow-
ing example, IR 00000, IR 00001, IR 00002, and IR 00003 are combined in a
logic block that stores the resulting execution condition as the status of
IR 21600. IR 21600 is then combined with various other conditions to determine
output conditions for IR 20000, IR 20001, and IR 20002, i.e., to turn the outputs
allocated to these bits ON or OFF.
21600
00005
20000
00005
20001
20002
Address Instruction
00000 LD
00001 AND NOT
00002 OR
00003 OR NOT
00004 OUT
00005 LD
00006 AND
00007 AND NOT
00008 OUT
00009 LD
00010 OR NOT
00011 AND
00012 OUT
00013 LD NOT
00014 OR
00015 OR
00016 OUT
Section 6-5
Operands
00000
00001
00002
00003
21600
21600
00004
00005
20000
21600
00004
00005
20001
21600
00006
00007
20002
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