Mitsubishi Electric MELSEC-Q Structured Programming Manual page 252

FXCPU Structured Programming Manual
[Device & Common]
PLC
Error operation
code at error
occurrence
Operation error [M8067(D8067)]
The measured value variation exceeds the limit.
6742
(ΔPV < -32768 or 32767 < ΔPV)
The deviation exceeds the limit.
6743
(EV < -32768 or 32767 < EV)
The integral result exceeds the limit.
6744
(Outside the range from -32768 to 32767)
The derivative value exceeds the limit due to the
6745
derivative gain (K
The derivative result exceeds the limit.
6746
(Outside the range from -32768 to 32767)
The PID operation result exceeds the limit.
6747
(Outside the range from -32768 to 32767)
PID output upper limit set value < PID output lower
6748
limit set value
The PID input variation alarm set value or output
6749
variation alarm set value is abnormal (Set value < 0).
<Step response method>
6750
The auto tuning result is improper.
<Step response method>
6751
Auto tuning operation direction mismatch
Continues
operation
<Step response method>
6752
The auto tuning operation is improper.
<Limit cycle method>
6753 The output set value for auto tuning is abnormal.
[ULV (upper limit) ≤ LLV (lower limit)]
<Limit cycle method>
The PV threshold (hysteresis) set value for auto
6754
tuning is abnormal.
(SHPV < 0)
<Limit cycle method>
The auto tuning transfer status is abnormal.
6755
(Data of a device which controls the transfer status is
overwritten abnormally.)
<Limit cycle method>
The result is abnormal due to excessive auto tuning
6756
measurement time.
(τ on > τ, τ on < 0, τ < 0)
<Limit cycle method>
6757 The auto tuning result exceeds the proportional gain.
(K = Outside the range from 0 to 32767)
P
250
Contents of error
) beyond the limit.
D
5.1 FX3S/FX3G/FX3GC/FX3U/FX3UC PLCs
Action
<The PLC continues PID operation.>
The PLC continues operation with each parameter set to the
maximum or minimum value.
<The PLC transposes the output upper limit value and the output
lower limit value each other, and continues PID operation.>
Confirm that the target setting contents are correct.
<The PLC does not output alarm, and continues PID operation.>
Confirm that the target setting contents are correct.
<The PLC finishes auto tuning, and starts PID operation.>
• The deviation at the start of auto tuning was 150 or less.
• When auto tuning was finished, the difference was 1/3 or more of
the difference at the start of auto tuning.
Check the measured value and target value, and then execute tuning
again.
<The PLC forcibly finishes auto tuning, and does not start PID
operation.>
The operation direction estimated from the measured value at the
start of auto tuning did not agree with the actual operation direction
caused by the output for auto tuning.
Correct the relationship among the target value, output value for auto
tuning and measured value, and then execute auto tuning again.
<The PLC finishes auto tuning, and does not start PID operation.>
The PLC did not execute auto tuning correctly because the set value
fluctuated during auto tuning.
Set the sampling time to a value sufficiently longer than the output
change cycle, or set the input filter constant to a larger value.
After changing the setting, execute auto tuning again.
<The PLC forcibly finishes auto tuning, and does not start PID
operation.>
Confirm that the target setting contents are correct.
<The PLC forcibly finishes auto tuning, and does not start PID
operation.>
Confirm that devices occupied by the PID instruction are not
overwritten in the program.
<The PLC forcibly finishes auto tuning, and does not start PID
operation.>
The auto tuning time is longer than necessary.
Increase the difference (ULV - LLV) between the upper limit and the
lower limit of the output value for auto tuning, set the input filter
constant (α) to a smaller value, or set the PV threshold (SH
auto tuning to a smaller value, and then check whether the situation
is improved.
<The PLC finishes auto tuning (K
operation.>
The variation of the measured value (PV) is small compared with the
output value.
Multiply the measured value (PV) by "10", for example, so that the
variation of the measured value will increase during auto tuning.
5 Errors
) for
PV
= 32767), and starts PID
P