Omron CVM1D Operation Manual page 106

Data Areas, Definers, and Flags
Basic Ladder Symbol
Variations
Operand Data Area
Precautions
Ladder Symbol
(022)
BCMP S
Variations
j BCMP(022)
! Caution
The ladder symbol shows how the instruction will appear in a program. The func-
tion code (here, 143) is provided above the mnemonic (SEC) and the operands
are provided to the right (here, S and R). The ladder symbol is the same for any
of the variations of the instruction except that the mnemonic changes.
The alternate forms of the instruction are listed here, including immediate re-
fresh and differentiated forms.
The data areas are listed that can be used for each instruction. The actual oper-
and will be a number, such as a word address, a bit address, an indirect address,
or a constant, depending on the requirements of the instruction and the needs of
the program.
Not all addresses in the specified data areas are necessarily allowed for an oper-
and, e.g., if an operand requires two words, the last word in a data area cannot
be designated as the first word of the operand because all words for a single op-
erand must be within the same data area. Refer to Section 3 Memory Areas for
addressing conventions and the addresses of specific flags and control bits.
For example, the second operand (CB) in the BLOCK COMPARE instruction
(BCMP(022), shown below) specifies the first word of a comparison table that is
32 words long. This operand thus cannot be any of the last 31 words in an data
area, e.g., if the CPU Bus Link Area is used, the last word that could be desig-
nated would be G224. Designating G245 would cause an error and the instruc-
tion would not be executed.
CB R
Note: The DM Area, IR, and DR are not listed as operand data areas unless they can
be addressed directly. These areas can be used for indirectly addressing oper-
ands provided that the address being pointed to is a legal address. For example,
for BCMP(022) (shown above) and Index Register could be used to indirectly
address a DM address for the second operand, CB. Refer to the discussion on
Indirect Addressing later in this section.
The Auxiliary Area words between A000 and A255 and the CPU Bus Link Area
words G008 through G255 can be read from or written to from the user program.
A256 to A511 and G000 to G007, however, can be read from to access the data
provided there, but cannot be written to from the user program, i.e., they cannot
be used as operands if the instruction alters the contents of the operand during
processing.
Designating Constants
Although data area addresses are most often given as operands, many oper-
ands can be input as constants. The available value range for a given operand
depends on the particular instruction that uses it. Constants must also be en-
tered in the form required by the instruction, i.e., in BCD or in hexadecimal.
Constants are also input as either four digits or as either digits, depending on the
requirements of the instruction (e.g., constants for double, or long, instructions
require eight digits).
Operand Data Areas
S: Source data CIO, G, A, T, C, #, DM, DR, IR
st
CB: 1 block word CIO, G, A, T, C, DM
R: Result word CIO, G, A, T, C, DM, DR, IR
Section 5-3
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