Allen-Bradley 1756-CFM, Руководство пользователя

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88 Rockwell Automation Publication 1756-UM010C-EN-P - June 2021
Chapter 5 Configure the Configurable Flowmeter Module
Sample Configuration for
High Resolution
Frequency Mode
High Resolution Frequency mode provides speed control of machinery such as
turbines where shutdown on acceleration or speed is required independent of
the owner-controller. Speed is calculated without the K-factor but includes the
meter factor and CCF for special calculations.
When using this mode, you can calculate resolution by using this equation to
calculate resolution.
The values listed in Table 6 are listed for example purposes. Specific values will
change according to your application.
This section offers a sample configuration to configure your module for High
Resolution Frequency mode. In this configuration, channel 0 is configured
and channel 1 is left unused.For a detailed explanation of the features available
in this mode, see
page 31 .
Follow the steps below to configure your module for High Resolution
Frequency mode.
1. Create a new module, see page 72 .
2. Set all communications options, including:
• name
• communication format
• slot number
• minor revision
• electronic keying
• RPI - For this application, the minimum RPI = 5 ms
See pages 73 to 76 .
Table 6 - Sample Resolutions
F
in
T
sample
Resolution
60Hz 0.033 seconds 0.00045Hz
5000Hz 0.020 seconds 0.0625Hz
50,000Hz 0.050 seconds 0.25Hz
F
in
(250 x 10
-9
)
T
sample
Resolution =
Where:
• F
in
is the input frequency
• T
sample
is the sample time period