WEG CFW700 Serie Manual Del Usuario página 35

Keypad (HMI) and Basic Programming
Application examples:
Flow control or pressure in a pipe system.
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Temperature of a furnace or oven.
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Dosing of chemicals in tanks.
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The following example defines the terms used by the PID controller.
A pump used in a water pumping system where is necessary to control the pressure of the
pipe. A pressure transducer is installed in the pipe and supplies an analog feedback signal
to the CFW700, which is proportional to the water pressure. This signal is called the process
variable, and can be visualized at the parameter P1012. A setpoint is programmed in the
CFW700 via keypad (P1025), through an analog input (such as a 0-10 V or 4-20 mA signal) or
via communication network. The setpoint is the desired water pressure value that the pump is
supposed to produce, regardless of the consumption variations at the pump output at any time.
It is necessary to set the parameter P0221 or P0222 to 7 = SoftPLC for the operation of the
PID Regulator application.
Definitions:
The Function 1 of the Application at parameters P0231 or P0236 represents the value of
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the PID Setpoint.
The Function 2 of the Application at parameters P0231 or P0236 represents the value of
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the PID Feedback.
The Function 1 of the Application at parameters P0251 or P0254 represents the value of
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the PID Setpoint.
The Function 2 of the Application at parameters P0251 or P0254 represents the value of
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the PID Feedback.
The Function 1 of the Application at parameters P0263 or P0270 represents the value of the
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Manual/Auto command.
The Function 1 of the Application at parameters P0275 to P0279 represents the VP>VPx
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logical condition.
The Function 2 of the Application at parameters P0275 to P0279 represents the VP<VPy
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logical condition.
The PID setpoint can receive an analog input signal (AI1 or AI2). It is necessary to set P1016
to 1 = AIx and select which analog input will be used. The analog inputs are set at P0231 (AI1)
or P0236 (AI2) and it is necessary to program it to 5 = Function 1 of the Application in order to
enable the analog inputs for the operation. The following alarm message will be displayed in
case it is not properly done: "A770: Set AI1 or AI2 for Function 1 of the Application".
The PID setpoint value can be presented via analog output AO1 or AO2. It is necessary to set
P0251 (AO1) or P0254 (AO2) to 17 = Function 1 of the Application. The full scale value of the
variable is 100.0 % and corresponds to 10 V or 20 mA.
30 | CFW700