Mitsubishi Electric MELSEC FX2N-2LC, User Manual

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FX2N-2LC Temperature Control Block Buffer Memory (BFM) 7
7-13
7
7.2.22 BFM #39 (CH1) and BFM #58 (CH2): Output change ratio limiter
In BFM #39, set the output change ratio limiter of CH1. In BFM #58, set the output change
ratio limiter of CH2.
The output change ratio limiter function limits the variation of the control output value (MV) per
unit time (1 sec). The output is limited in accordance with the preset output change ratio.
The allowable set range is from 0 to 100%.
When BFM #39/#58 is set to "0.0%", the output change ratio limiter function is disabled.
When the power is turned on (outside the proportional band) or when the set value is consider-
ably changed, the output does not drastically change but is performed in accordance with the
preset inclination.
- When the output change ratio limiter is set to a small value (that is, when the inclination
is small), the control response becomes slow and the effect of differential is eliminated.
- While two-position control is performed, the output change ratio limiter is disabled.
- While the output change ratio limiter is effective, proper PID constants may not be
obtained during auto tuning. It is recommended not to use the output change ratio limiter
when auto tuning is used.
When the output change ratio limiter is not used
0.1 to
100.0%
1 sec
Output limiter (upper limit)
Output limiter (lower limit)
Drastic changes in output
caused by power ON, change of
the set value, disturbance, etc.
Set how many percentages the
operation output is to be
changed in a second.
Operation output value
(MV)
Operation output value
(MV)
Output
drastically
changes.