Bfm#67][Bfm#107][Bfm#147][Bfm#187] Output Change Ratio Limiter - Mitsubishi Electric MELSEC FX Series User Manual

FX -4LC User's Manual
3U

8.2.31 [BFM#67][BFM#107][BFM#147][BFM#187] Output change ratio limiter

The output change ratio limiter function limits changes in the control output value (MV) per unit time (1 sec).
The preset output change ratio limits the control output.
The output does not change drastically but is given in accordance with the preset inclination when the power
is turned ON (and the output is outside the proportional band) or when the set value is changed (significantly).
BFM No.
CH1 CH2 CH3 CH4
#67 #107 #147 #187
*1. These buffer memories can be written only while standard PID control is being performed.
Example of operation
Output limiter upper limit
Control output value (MV)
Output
drastically
changes
Control output value (MV)
Output limiter lower limit
Caution
• Handling numbers containing decimal places. The set value should be the actual value multiplied by 10.
• Entering a small value to these buffer memories (to make the inclination smaller) makes the control
response slow, and eliminates the derivative effect.
• The output change ratio limiter is disabled while two-position control is being performed.
• The output change ratio limiter is disabled while heating/cooling PID control is being performed.
• The output change ratio limiter is disabled when "0" is entered to these buffer memories.
• Proper PID constants may not be obtained if the output change ratio limiter is set and auto tuning is
performed.
Do not set the output change ratio limiter when performing auto tuning.
Description
Setting range :
• PID control :
0 to 1000 (0.0 to 100.0%/sec.)
• Heating/cooling PID control :
0 (Not used)
When the output change ratio limiter is not used
Drastic changes in output
caused by power ON, change of
the set value, disturbance, etc.
8.2 Buffer Memory Details
Initial
value
0
0.1 to
100.0%
1 sec.
Set how many percentages the
operation output is to be
changed in 1 sec.
8 Buffer Memory
1
2
R/W Backup
*1
R/W
3
4
5
6
7
8
9
10
95