Delta AH500 Manual page 207

Ch a pt er 6 Tem per at u r e M eas ur em ent M o d u le A H 04T C / AH 08T C
Control diagram:
T he instruction PID is inside the dotted line.
+
-
The PID algorithm is as follows.
t
( )
∫
MV K E t K E
= +
) (
P I
0
( )
E t
Forward action:
( )
E t
Reverse action:
b. Control mode
Cyclic control mode: Users set a cycle according to a controlled environment. (If the ambient
air temperature changes slowly, the cycle can be longer.)
The width of a pulse is defined below.
 Pulse width=Output value (MV)/(Maximal output value–Minimal output value)×Cycle
Users can set the width of a pulse and a cycle (sampling time) by means of the instruction
GPWM.
Example:
The cycle is 2000 ms, the maximal output value is 100, and the minimal output value is 0. After
the PID algorithm is performed, the output value gotten is 50.
 Width of a pulse=50/(100-0)×2000 ms=1000 ms
Therefore, the pulse width used in the instruction GPWM is 1000 ms, and the cycle used in the
instruction GPWM is 2000 ms.
1/K
1/S
I
+
K
S
D
dE t
) (
t dt K
+
*
D
dt
( ) ( )
=
PV t - SV t
( ) ( )
=
SV t - PV t
+
1/K
G(s)
P
+
6 - 11