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How To Use Interlock Instruction (IL/ILC)

The Interlock Instructions can be used to turn OFF all the sequence outputs from a specific program block, as might be necessary to process an emergency stop for one line.

Basic Specifications of INTERLOCK Instruction (IL)

When the execution condition for IL is ON, all bits specified for the following three instructions that are located between IL and ILC instructions in the ladder program will be turned OFF.
  • OUT instruction
  • OUT NOT instruction
  • OUTB instruction (See note.)

Note:This instruction can be used on the following CPU Units: CS1-H/CJ1-H/CJ1M Programmable Controllers.

Ladder Program Sequence When Interlock Is Not Active  

Refer to Figure 1.
* The execution condition for the IL instruction is ON. The instructions between the IL and ILC instructions will be executed as normal. Outputs A to D (CIO 2.00 to CIO 2.03) are all ON. SINGLE BIT OUTPUT (OUTB) Instruction causes the bit 15 of D100 to be turned ON (D100: 8000 hex)

IL ladder diagram showing Outputs OFF

Ladder Program Sequence When Interlock Is Active  

Refer to Figure 2.
*The execution condition for the IL instruction turns OFF. The bits CIO 2.00 and CIO 2.01 in the OUT and OUT NOT instructions that are within the IL and ILC Instructions will be turned OFF. The OUTB instruction will turn OFF bit 15 of D100. (D100: "8000" to "0000" hex) (See note.) Bits CIO 2.02 and CIO 2.03, which kept ON using the KEEP and SET instructions, will not be turned OFF.

Note:Other bits in D100 will not be turned OFF even if they are used in instructions other than the OUTB instruction (e.g., MOV).

IL output OFF ladder diagram

IL Output OFF

CIO 000000: Device interlock bit (CIO 0.00)
CIO 000200: Output A (CIO 2.00)
CIO000201: Output B (CIO 2.00)
CIO 000202: Output C (CIO 2.02)
CIO 000203: Output D (CIO 2.03)

When the device interlock bit (CIO 0.00) turns ON, outputs A and B (CIO 2.00 and CIO 2.01) turn OFF, and outputs C and D (CIO 2.02 and CIO 2.03) stay ON. D100 changes from 8000 to 0000 hex.
Note:If there are outputs that you do not want to turn OFF when the interlock is enabled in the same program block, use the KEEP instruction or SET/RESET instructions, as mentioned before.

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Created 2008-11-06
Modified 2013-06-12
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