Rockwell Automation 1756-CFM ControlLogix Configurable Flowmeter Module - Manual (Page 97)

97 Rockwell Automation Publication 1756-UM010B-EN-P - December 2011
Configuring the Configurable Flowmeter Module 97
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 may calculate resolution by using the following
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 CFM 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 36 .
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