Bit Device Output Reverse (Chk) - Mitsubishi MELSEC A1SCPU Handy Manual

Bit device output reverse (CHK)
Y10 OFF
Output reverse command
Required device number
Dummy data
Step Number
0
1
The CHK instruction has two functions, one which operates when the CPU is in refresh
mode (default), and the other when the CPU is in direct mode. When the CPU is in
refresh mode the specified device (DI), has its output status reversed when the
operation result from the preceding devices turns from OFF to ON. Dummy data needs
to be input for (D2), however the status of the device specified by (D2) is unchanged
and can be used freely throughout the sequence program. When the CPU is in direct
mode the CHK instruction carries out a 'failure check'. This function is classified as an
application instruction and is described in the relevant section of the programming
manual.
An example of the CHK instruction is shown below
Instruction Device
LD X I
CHK Y10 DO
ON
X5 OFF
113