Watlow Controller Series D8, Руководство пользователя

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D8 Series User’s Guide
Chapter 4: Operation and Setup
86
Remote Analog Set Point Example: Changing a Set Point with a PLC
A PLC provides a 0 to 5VDC signal representing 0 to 300°F as a remote set point input to the D8.
The input signal is received on loop 1, and control is performed on loop 2. The D8 is equipped with
the proper scaling resistors to allow it to accept a 0 to 5VDC input.
Table 4.13 and Table 4.14 show the parameter settings for this application.
Table 4.13 – Parameters Settings for the Master Loop (Loop 1) in the Example
MENU PARAMETER VALUE COMMENT
Input Input type process
A 0 to 5VDC input signal is a process input.
Input Input range high 300.0° F
The 5VDC input signal represents 300°F.
Input Input high signal 100.0%
The controller is equipped with a 0 to 5VDC
input, and the input signal is 0 to 5VDC,
so the signal covers the full scale of 0 to
100 percent.
Input Input range low 0° F
The 0VDC input signal represents 0° F.
Input Input low signal 0.0%
The controller is equipped with a 0 to 5VDC
input, and the input signal is 0 to 5VDC,
so the signal covers the full scale of 0 to
100 percent.
Table 4.14 – Parameter Settings for the Ratio Loop (Loop 2) in the Example
MENU PARAMETER VALUE COMMENT
Ratio Ratio master loop 01
Loop 1 is the master loop (receives the input
signal from the external device).
Ratio Ratio low SP 0° F
For this example, we will assume that the
process can be set safely over the entire
range of 0 to 300°F. If desired, we could set a
more restrictive range for the ratio loop.
Ratio Ratio high SP 300.0° F
Ratio Control ratio 1.0
For this example, we want to retain the
original input value, so we will multiply it
times 1.0.
Input Ratio SP diff 0
For this example, we want to retain the
original value, so we will add 0.
To complete the setup, loop 2 must be configured for inputs, outputs, and alarms. In addition, loop 1
may be configured for outputs and alarms.