3. INSTRUCTION STRUCTURE
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MELSEC-A
(2) Error processing
If an operation error has occurred during the execution of basic instructions or
application instructions, the error flag (M9010, 9011) is turned on and the error
step number is stored into the error step storage register (D9010, 9011).
1) D9011 stores the step number of the instruction which has caused an
operation error when M9011 changes from off to on. Therefore, if M9011
remains on, the contents of D9011 do not change.
2) Program the reset of M9011 and D9011 as shown below.
Fig. 3.10 Resetting the Special Relay, Register
3) If an operation error has occurred, sequence processing may be stopped or
continued as selected by the parameter setting. For details, refer to the
ACPU Programming Manual (Fundamentals).
Error flag
*M9010……….Turned on by operation error and turned off when the next basic instruction o
application instruction is valid.
M9011………...Turned on and latched by the first operation error.
*Not provided to A3H, A3M, AnA, A2AS, AnU, QCPU-A (A Mode) and
A2USH board.
Error step storage register
D9010………...Stores the head step number of the instruction which has caused the operation
error.
D9011………...Stores the head step number of instruction which has caused operation error first.
The stored step number is latched.
Resets (turns off) M9011.
Resets D9011.
(Changes the content of D9011 to 0.)
Reset command
Reset command
RST M9011
RST D9011
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