Bfm#63][Bfm#103][Bfm#143][Bfm#183] Overlap/Dead Band - Mitsubishi Electric MELSEC FX Series User Manual

FX -4LC User's Manual
3U

8.2.27 [BFM#63][BFM#103][BFM#143][BFM#183] Overlap/Dead band

To these buffer memories, set the range of the overlap area or dead band for heating/cooling PID control.
Enter a value in the range from -100 to -1 (negative value) to set the overlap area.
Enter a value in the range from +1 to +100 (positive value) to set the dead band.
Set "0" not to use the overlap area or dead band.
BFM No.
CH1 CH2 CH3 CH4
#63 #103 #143 #183
*1. Input span for internal temperature input
Scaling span for internal micro voltage input
External input span for external input
*2. These buffer memories can be written only while heating/cooling PID control is being performed.
Explanation of operation
Overlap:
The proportional band on the heating side and proportional band on the cooling side overlap in the overlap
area.
When the measured value (PV) is located within the overlap area, both the control output on the heating side
and the control output on the cooling side are given at the same time.
Dead band:
The dead band (dead zone) is located between the proportional band on the heating side and the proportional
band on the cooling side.
When the measured value (PV) is located within the dead band, both the control output on the heating side
and the control output on the cooling side are not output.
Control output value (MV)
100%
0%
Caution
• The setting of the overlap area/dead band is invalid while two-position control is being performed.
• These buffer memories store "0" while standard PID control is being performed. (Not used)
• Set the overlap area within the proportional band setting range.
92
→ For details on the overlap/dead band, refer to Subsection 6.6.3.
Setting range :
• PID control :
0 (Not used)
• Heating/cooling PID control :
-100 to +100 (-10.0 to +10.0% of span)
Heating
proportional
band
Heating
output value
Set value(SV)
Overlap
Description
*1
Cooling
proportional
band
Dead
band
8 Buffer Memory
8.2 Buffer Memory Details
Initial
R/W
value
*2
0
R/W
Cooling
output value
Measured
value (PV)
Backup