Debugging And Failure Diagnosis Instructions - Mitsubishi MELSEC Q Series Programming Manual

CHKST,CHK
7.10

Debugging and failure diagnosis instructions

7.10.1
Special format failure checks (CHKST,CHK)
CHKST,CHK
CHKST
CHK
Setting
Data
––
Function
CHKST
(1) The CHKST instruction is the instruction that starts the CHK instruction.
If the command for the CHKST instruction is OFF, execution jumps from the CHK instruction
to the next instruction.
If the command for the CHKST instruction is ON, the CHK instruction is executed.
CHK
(1) The CHK instruction is the instruction used for the bidirectional operation as shown on the
following page to confirm the nature of the system failure.
(a) When the CHK instruction is executed, a failure diagnosis check is conducted with the
designated check conditions, and if a failure is detected, SM80 is turned ON, and the
failure number is stored at SD80 as a BCD value.
The error code "9010" will be returned if a failure is detected.
The contact number where the failure was discovered is stored at the upper 3 digits of
SD80 (see (3)), and the coil number where the failure was detected (see (2)) is stored at
the lower 1 digit of SD80.
7-174
Command
X
Check condition (Only a contact is valid; b contact is ignored)
Up to 150 contacts can be connected
Internal Devices
R, ZR
Bit Word
When T0 is OFF,
program jumps to the
instruction next to the
CHK instruction.
Before the detection of failure
SM80 OFF
SD80 0 0 0 0
High
Basic
performance
X X
Only input (X) can be used
J \
U \G
Bit Word
––
TO
X0 X2
At the detection of failure of
Contact No.: 62, Coil No.: 3
Process
Redundant Universal LCPU
CHKST
X
CHK
Zn Constants Other
CHKST
CHK
Y10
After the detection of failure
SM80 ON
SD80 0 6 2 3