Emerson Daniel 3410 Series Operation Manual page 49

Operations manual
DAN-20057316
The triggered delta volume functionality is retained across power cycles as the
accumulated volumes values at the last event trigger are saved in non-volatile memory.
The delta volume data points are stored internally in non-volatile memory as double-
precision floating point numbers. The delta volume data points can be read via Modbus as
either 32-bit floating point values or as integer values (using the [overflow,lower] LONG
register pair in a manner similar to reading the accumulated volumes).
Suggested user access logic
The following pseudo-code demonstrates the logic to access the triggered delta volume
functionality:
• INITIAL SET-UP:
Ensure Modbus units are set-up as desired: set Modbus register 10026 (UnitsSystem)
to 0 for U.S. Customary units or to 1 for metric units.
• Periodic Loop:
Wait for external event for synchronizing the start of the meter delta volumes.
Send trigger Modbus message: set Modbus register 12199 (DoUpdtTrigDeltaVols) to 1
(TRUE).
Read trigger Modbus register 12199 (DoUpdtTrigDeltaVols) in a loop until it is read as
0 (FALSE) indicating that the delta volumes have been updated.
Read delta volume registers (either the FLOAT registers or the LONG register pairs) in a
single Modbus read. If the delta volume registers are read as LONG register pairs, calculate
each delta volume as follows:
Equation 5-5: Triggered delta volume
where
DeltaVolume = triggered delta volume (forward or reverse, flow-condition or base-
condition) (m
TrigDeltaPosVolBase, TrigDeltaNegVolBase)
Overflow = triggered delta volume overflow integer value (forward or reverse, flow-
condition or base-condition) (1e
Lower = triggered delta volume lower integer value (forward or reverse, flow-condition
or base-condition) (m
Repeat "PERIODIC LOOP"
5.1.2 Configure operational parameters
Table 5-5: Configure Operational parameters
Calibration selection
Analog inputs and outputs
(Calibrate analog inputs
and outputs)
Meter factors
meter
Model 3418 GUSM
DeltaVolume = Overflow × 1e9 + Lower
3 3
) (TrigDeltaPosVolFlow, TrigDeltaNegVolFlow,
or ft
3
or ft
Description
Calibration settings for the pressure and temperature analog inputs.
(Calibrate Calibration settings for the pressure and temperature analog inputs.
factors)
9 3 9 3
m or 1e ft )
3
)
Configurations
January 2019
49