19
Applications
19-8 | CFW700
19.2.4 Monitoring Mode Screens
When PID regulator application is used, the monitoring screen can be configured to show the main variables in
numerical form, which may or may not have engineering units.
An example of the keypad with this setting can be seen in
, which are shown: the process variable
and the setpoint, both without engineering unit (referenced to 25.0 bar) and the motor speed on the bar graph in
percentage (%). Refer to
Figure 19.3:
Keypad monitoring mode for the PID regulator application
19.2.5 Connection of a 2-Wire Transducer
In the 2-wire configuration the transducer signal and its supply share the same wires. The
this type of connection.
Setpoint
via keypad
CFW700
OFF ON
1
2
S1
PE R S T U V W PE
3
4
Pressure
Transducer
Process
37
39
40
35
34
36
21
22
23
24
25
26
DI1
DI3
DI4
COM
24 VDC
DGND
+REF
AI1+
AI1-
-REF
AI2+
AI2-
Figure 19.4:
Connection of a 2-wire transducer to the CFW700
19.2.6 Academic PID
The PID regulator implemented in the CFW700 is the academic type. The equations that characterize the Academic
PID, which is the base of this function algorithm, are presented next.
The transfer function in the Academic PID regulator frequency dominion is:
y(s) = Kp x e(s) x [ 1 + 1 + sTd ]
sTi
By replacing the integrator by a sum and the derivative by the incremental quotient, one gets an approximation
for the discrete transfer equation (recursive) presented next:
y(k) = y(k-1) + Kp[(1 + Ki.Ta + Kd/Ta).e(k) – (Kd/Ta).e(k-1)]
Being:
y(k): current PID output can vary from 0.0 to 100.0 %.
y(k-1): PID previous output.
Kp (Proportional gain): Kp = P1020.
Ki (Integral gain): Ki = P1021 x 100 = [1/Ti x 100].
Kd (Differential gain): Kd = P1022 x 100 = [Td x 100].
Ta = 0.05 sec (PID regulator sampling time).
Summary of Contents for CFW700
Page 2: ......
Page 4: ......
Page 8: ...Summary...
Page 34: ...2 General Information 2 4 CFW700...
Page 38: ...3 About the CFW700 3 4 CFW700...
Page 56: ...7 Starting up and Settings 7 4 CFW700...
Page 58: ...8 Available Control Types 8 2 CFW700...
Page 78: ...10 VVW Control 10 8 CFW700...
Page 158: ...13 Digital and Analog Inputs and Outputs 13 28 CFW700...