Rockwell Automation 1756-CFM ControlLogix Configurable Flowmeter Module - Manual (Page 42)

42 Rockwell Automation Publication 1756-UM010B-EN-P - December 2011
42 Configurable Flowmeter Module Features and Operational Modes
Using the Totalizer Mode
Prover Function
In the Totalizer Mode Prover function, the CFM module interfaces to a prover
and counts pulses using a Flowmeter or positive displacement meter. The
module then scales pulse count to engineering units. The CFM module can
also use this mode to calculate frequency over a user-defined time period,
where frequency is calculated as counts per unit time.
Either module output can be tied to either flowmeter input with the Prover
function, and output operation can occur independently from new data from
the Logix owner-controller.
With the Prover function, the totalizer is active all the time, but the Prover
function must first be enabled and started to activate the Prover Total. Once
the Prover function is started, only the gate signal or a user-override (i.e.
clearing the Prover Enable bit) can eliminate the function. However, the Gross
Volume, Net Volume, and Fill Total will continue to accumulate as long as the
flow input frequency is enabled and is greater than Low Frequency Clear.
This figure shows a 1756-CFM module in a petrochemical flow and custody
transfer application while operating in the totalizer mode prover function.
42731
1756-CFM
Logix controller:
 performs AGA/API calculations
 controls prover
 calculates/compensates based
on actual temperature
1756-IF6I
monitor fuel flow and total gallons
Remote
Termination
Panel
TT
PT
FT
prover