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FX Series Programmable Controllers Basic Program Instructions 2
2-11
2.11 Or Block
Program example:
Basic points to remember:
- An ORB instruction is an independent instruction and is not associated with any device
number.
- Use the ORB instruction to connect multi-contact circuits (usually serial circuit blocks) to
the preceding circuit in parallel. Serial circuit blocks are those in which more than one
contact connects in series or the ANB instruction is used.
- To declare the starting point of the circuit block use a LD or LDI instruction. After
completing the serial circuit block, connect it to the preceding block in parallel using the
ORB instruction.
Mnemonic Function Format Devices Program steps
ORB
(OR Block)
Parallel connection
of multiple contact
circuits
N/A 1
X0 X1
X2 X3
ORB
X4 X5
ORB
LD
AND
LD
AND
ORB
ORB
LDI
AND
0
1
2
3
4
6
7
5
8 OUT
X
X
X
X
X
0
1
2
3
4
Y
X
5
6
LD
AND
LD
AND
LDI
ORB
AND
ORB
0
1
2
3
4
6
7
5
8 OUT
X
X
X
X
X
0
1
2
3
5
Y6
X4
Recommended sequential
programming method
Non-preferred batch
programming method
Y6
Batch processing limitations:
• When using ORB instructions in a batch, use no more than 8 LD and LDI instructions
in the definition of the program blocks (to be connected in parallel). Ignoring this will
result in a program error (see the right most program listing).
Sequential processing limitations:
• There are no limitations to the number of parallel circuits when using an ORB
instruction in the sequential processing configuration (see the left most program
listing).