Omron CJ - INSTRUCTIONS REFERENCE MANUAL 07-2009 Reference Manual page 174

Hint
• LD/LD NOT is used in the following circumstances as an instruction for indicating a logical start.
1. When directly connecting to the bus bar.
2. When logic blocks are connected by AND LD or OR LD, i.e., at the beginning of a logic block.
The AND LOAD and OR LOAD instructions are used to connect in series or in parallel logic blocks
beginning with LD or LD NOT.
• At least one LOAD or LOAD NOT instruction is required for the execution condition when output-
related instructions cannot be connected directly to the bus bar. If there is no LOAD or LOAD NOT
instruction, a programming error will occur with the program check by the Peripheral Device.
• When logic blocks are connected by AND LOAD or OR LOAD instructions, the total number of AND
LOAD/OR LOAD instructions must match the total number of LOAD/LOAD NOT instructions minus1.
If they do not match, a programming error will occur. For details, refer to 3-3-7 AND LOAD: AND LD
and 3-3-8 OR LOAD: OR LD.
Precautions
• Differentiate up (@) or differentiate down (%) can be specified for LD. If differentiate up (@) is
specified, the execution condition is turned ON for one cycle only after the status of the operand bit
goes from OFF to ON. If differentiate down (%) is specified, the execution condition is turned ON for
one cycle only after the status of the operand bit goes from ON to OFF.
• Immediate refreshing (!) can be specified for LD/LD NOT. An immediate refresh instruction updates
the status of the input bit just before the instruction is executed for Basic Input Units (but not Basic
Input Units on Slave Racks or for C200H Group 2 Multi-point Input Units).
• For LD, it is possible to combine immediate refreshing and up or down differentiation (!@ or !%). If
either of these is specified, the input is refreshed from the Basic Input Unit just before the instruction
is executed and the execution condition is turned ON for one cycle only after the status goes from
OFF to ON, or from ON to OFF.
• With CJ2 CPU Units, LD and LD NOT can be used for bits in the DM or EM Area. For other models of
CPU Unit, LD and LD NOT cannot be used for bits in the DM or EM Area. Use LD TST(350) and LD
TSTN(351) instead.
Sample program
LD
0.01
0.00
0.02
0.04
0.05
LD NOT
CS/CJ/NSJ Series Instructions Reference Manual (W474)
LD
1.00
LD
0.03
i
Instruction Operand
LD 0.00
OR LD
LD 0.01
LD 0.02
AND 0.03
OR LD --
AND LD --
LD NOT 0.04
AND 0.05
OR LD --
OUT 1.00
3. Instructions
AND LD
OR LD
137
3