Unipulse F805AT-BC, Operation Manual

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6.SETTING AND ADJUSTMENT OF READING
82
6-8-1. How to assign code
Operation
F805AT-BC uses two types of codes: one for weighing (Weighing Code) and the other
for settings (Setting Code).
6-8-2. PID control
F805AT-BC uses feedback control to control instantaneous feed rate. In this scheme,
calculated target value is compared with actual feed rate and the deviation between
them is returned to nullify the difference (see the schematic diagram below).
For implementing feedback control, F805AT-BC uses PID control method, which is a
combination of proportional (P), integral (I) and differential (D) action.
PID is well known for superb performance when applied to controlling systems with
dead time, or delay element. Proportional action (P) calculates proper control rate
taking all necessary elements (target value and environmental factors) into
consideration. Integral action (I) compensates the offset between target and actual
value. Differential action (D) accelerates system response against external
disturbances. Optimum feedback control is realized by proper tuning of P, I, D
parameters.
Currently selected code
Current weighing code Keys to select code number
number
MODE EACH CODE
→
F805AT-BC
（
PID control
）
Feeder
r
（
projected
u
（
control rate
） ＋
－
disturbance
y （ feed rate ）
e
（
control
＋
Control Diagram
target value
）
deviation
）