Manual

4–8 Configure the CFM Module
Publication 17716.5.99 - December 1995
You select the mode(s) of operation and configure each input channel
to accept input signals from your input device(s).
Totalizer and Nonresettable Totalizer Modes
These modes measure incoming pulses over a user-specified time
interval (4-1000ms). In either of these modes, the CFM module
calculates:
• rate of input (0-100,000Hz)
• total count (0-9,999,999)
• acceleration value
• optional prover value
• optional store count value (current count value)
BTR status and input data
1771CFM
F0
G0
input
device
BTW configuration
PLC processor
prover/store
Counting
In these modes, the CFM module counts pulses based on values you
enter in the BTW configuration block. You can specify these values:
Value BTW word # Use to
Rollover
13/14, 23/24, 33/34, 43/44
specify the value at which the CFM module will rollover to zero and begin
counting again. DEFAULT: 0 = 10,000,000 RANGE: 09,999,999
Important: Every time a rollover occurs, the CFM module changes the
state of the Overflow Status bit. (toggles between 0  1 every
time an overflow occurs). The Overflow Status can also be
manually reset in the BTW (word 1, bits 0003).
Overflow Reset 1 (bits 0407)
resets the overflow status of the CFM module for the appropriate input
channel. When this bit is set, the CFM module will reset the Overflow
Status (BTR words 4 & 5, bits 02 & 10). Overflow Status toggles between
0101 every time a rollover occurs. Overflow Status is not affected by
Total Reset.
Total Reset
(Totalizer mode only)
1 (bits 0003)
reset the total count to zero. This occurs on a change in bit state from a
0 to a 1. This value does not effect the Overflow Status
(BTR word 4 & 5, bits 2 & 10).
Total Scaler Multiplier 11, 21, 31, 41
scale the returned total count to actual engineering units.
For each value RANGE: 032,767 DEFAULT: 1
Total Multiplier must be < Total Divisor
Total Scaler Divisor 12, 22, 32, 42
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The scaled value can not be used to trigger any outputs (outputs triggered
by count are triggered by actual count).
Select the Mode(s)
of Operation
Use Totalizer mode if you:
• need counting (totalization) capabilities
• can measure frequency over a fixed
sampling period (4ms1s)
• need a frequency value
• need prover capabilities
• need count storage capabilities
• also want to calculate acceleration
Use Nonresettable Totalizer mode
if you want to use the features of the
Totalizer mode with NO BTW reset
capabilities.
Typical applications:
• measuring ingredients in a
batch process
• oil pipeline terminals (prover)