Recalculating a Previous Batch within the Flow Computer

Recalculating a Previous Batch within the Flow Computer
Last Updated: 03-June-2009
TB-980202C
Technical Bulletin,
Recalculating a Previous Batch
within the Flow Computer
OMNI FLOW COMPUTERS, INC.
12620 West Airport Boulevard, Suite 100
Sugar Land, Texas 77478 United States of America
Phone-281.240.6161 Fax: 281.240.6162
www.omniflow.com
52-0000-0009/Rev C
Page 1 of 8
TB-980202C
Recalculating a Previous Batch
within the Flow Computer
NOTE: User Manual Reference - This Technical Bulletin complements the information contained in
Volume 2, Chapter3 “Computer Batching Operations”, applicable to Revision 20/24.74+ and
22/26.74+.
The ‘+’ symbol following the firmware revision numbers indicates that all future revisions beyond
the stated revision are covered by this bulletin.
Batch Recalculation – The batch recalculation feature allows you to adjust quantities of the
previous four (4) batches at measurement locations where SG60/API60 and S&W values only
become available after the batch has been delivered.
Table of Contents
Scope ............................................................................................................................................3
Abstract .........................................................................................................................................3
Calculations Performed .................................................................................................................3
Using the Flow Computer Keypad to Recalculate a Previous Batch Ticket ..................................3
Step 1 ........................................................................................................................................3
Step 2 ........................................................................................................................................3
Step 3 ........................................................................................................................................4
Step 4 ........................................................................................................................................4
Step 5 ........................................................................................................................................4
How the Flow Computer Manages the Modbus Database............................................................4
Previous Batch Data that Is Read/Writable ...............................................................................5
Batch Recalculation Modbus Registers Meter “n” Batch Recalculation ........................................5
Versions 20.74+ and 24.74+ (Tables 3 and 4) ..........................................................................5
Modbus Communication Summary ...............................................................................................6
Meter “n” Batch Recalculation .......................................................................................................6
Applies to Versions 22.74+ and 26.74+ (Tables 5 and 6) .........................................................6
Modbus Communication Summary ...............................................................................................7
52-0000-0009/Rev C Page 2 of 8
TB-980202C
Recalculating a Previous Batch
within the Flow Computer
Scope
Firmware Revisions 20.74+ and 24.74+ of OMNI 6000/OMNI 3000 Flow Computers have the feature of
Batch Recalculation. This feature applies to Turbine/Positive Displacement/Coriolis Liquid Flow Metering
Systems (with K Factor Linearization. Firmware Revisions 22.74+ and 26.74+ have a similar feature.
However, the Modbus Data Points used to access data are different from those in Revisions 20/2.74+.
Abstract
The purpose of recalculating a previous batch is to make batch quantity corrections based on
SG60/API60 and Sediment and Water data becoming available via sample analysis performed after a
batch delivery is complete. At measurement locations where SG60/API60 and S&W values are not
available online, sampler devices continuously extract a representative sample of fluid during a batch. At
the end of the batch the sample container is sent for lab analysis. The data obtained from the analysis
report can then be used to recalculate the batch correction factors and therefore batch quantities.
Historical data from these analysis reports is also used to determine what values of SG60/API60 should
be used for real time calculation of future batches that are known to have similar characteristic. These
batches ultimately can also be recalculated when their actual analysis is determined.
Calculations Performed
The liquid correction factors Ctl and Cpl are first recalculated using the sample analysis SG60/API60 and
the batch flow weighted average temperature and pressure calculated during the batch.
Gross Standard Volume (GSV) is recalculated using the newly calculated Ctl and Cpl.
The Sediment and Water correction factor Csw is calculated using the sample analysis S&W%.
Net Standard Volume (NSV) is recalculated using the recalculated GSV and Csw factor.
Using the Flow Computer Keypad to Recalculate a Previous Batch Ticket
To ensure that previous batch data is correctly recalculated to not recalculate a batch
close to ending a current batch in progress.
NOTE: Only four (4) lines can be displayed at one time. Use the scroll up or down arrows keys to display
additional text.
CAUTION:
Step 1
Press [Prog] [Batch] [Meter] [n] [Enter] (n = meter run number). The OMNI LCD screen will
display:
METER #1 BATCH Print & Reset ? Select Prev# Batch Enter API60 .0 Enter SG60 .0000 Enter %S&W .00 Recalculating&Print?
Step 2
Select which previous batch you wish to recalculate. The OMNI stores the last four (4) completed
batches numbered as:
1 = last batch completed
to
4 = oldest batch completed
Press [↓] to scroll down to “Select Prev # Batch” and enter a number between one (1) and four (4),
depending upon which batch is to be recalculated.
52-0000-0009/Rev C Page 3 of 8
TB-980202C
Recalculating a Previous Batch
within the Flow Computer
The flow computer moves the selected previous batch data to the ‘previous batch’ data points within
the database (see explanation later in this document)
Step 3
Enter Password when requested.
Step 4
Scroll to either “Enter API60” or “Enter SG60”. Type in a valid value and press [Enter]
Step 5
Scroll to “Recalculate & Print?”. Press [Y] and then [Enter].
At this time the flow computer will recalculate the batch data and send the report to the printer and
the ‘Historical Batch Report Buffer’ in RAM memory. Batch report data can also be captured in ‘Raw
Data Archive RAM’ using the trigger Boolean 1n76. The default batch report shows the batch
number as XXXXXXXX where the number ahead of the ‘-‘ is the batch number (5n90) and the
number after the ‘-‘ is the number of times that the batch has been recalculated (3n52). Variable
(3n52) is reset to ‘0’ at the end of a batch and increments each time the batch is recalculated.
How the Flow Computer Manages the Modbus Database
NOTE: The second digit of the index number (indicated as “n”) defines which meter run you are working
with (i.e., n=1, 2, 3, or 4). A pointer mechanism has been utilized which avoids having to have duplicate data points for every batch
report variable for each of the four (4) previous batches. Only (1) one set of data points for previous
batch data are mapped within the Modbus database. A pointer register is used to determine which set of
previous batch data will be available by accessing the previous batch data points within the Modbus
database.
Using the batch gross totalizer variable as an example, we have:
•
•
•
Modbus address of Current Batch in Progress – Gross Totalizer is 5n01
Modbus address of Previous Batch – Gross Totalizer is 5n50
Modbus address of Pointer register to select which previous batch is mapped is 3n51
As the batch progresses the gross totalizer (5n01) accumulates flow. At the end of the batch the flow
computer performs the following actions:

#3 previous batch data replaces #4 previous batch data

#2 previous batch data replaces #3 previous batch data

#1 previous batch data replaces #2 previous batch data

Current batch data replaces #1 previous batch data

Pointer register 3n51 is set to the value ‘1’ so that the Modbus database addresses for previous batch
will access data for the batch just ended. This ensures that the batch report which prints immediately
at the end of a batch and gets it’s data from the Modbus database, includes the correct information.
Table 1 (using the batch gross totalizer as an example) shows typical data that would be read by
accessing Modbus points 5n01 and 5n50.
The data read depends upon the value of pointer register 3n51.
52-0000-0009/Rev C Page 4 of 8
TB-980202C
Recalculating a Previous Batch
within the Flow Computer
TABLE 1. Batch Gross Totalizer
STEP
CURRENT
BATCH
5n01
DESCRIPTION
Value contained in
Pointer register 3n51
1ST PREV.
BATCH
5n50
2ND PREV.
BATCH
5n50
3RD PREV.
BATCH
5nB0
4TH PREV.
BATCH
5n50
1
2
3
4
1
First batch running
12340
0
0
0
0
2
First batch ended
23450
12340
0
0
0
3
Second batch ended
34560
23450
12340
0
0
4
Third batch ended
45670
34560
23450
12340
0
5
Fourth batch ended
56780
45670
34560
23450
12340
6
Fifth batch ended with
sixth batch running
6123
56780
45670
34560
23450
Previous Batch Data that Is Read/Writable
All data points shown in Table 2 for previous batch transactions are ‘read/write’.
Table 2. Previous Batch Transactions
METER #1
METER #2
METER #3
METER #4
STATION
SG 60 or Reference
Density (Rev. 24.71)
8508
8608
8708
8808
8908
API 60 Gravity
8519
8619
8719
8819
8919
Sediment and Water
Percentage (BS&W)
8517
8617
8717
8817
8917
Command Boolean which
triggers the recalculation
2756
2757
2758
2759
1798
Batch Recalculation Modbus Registers Meter “n” Batch Recalculation
Versions 20.74+ and 24.74+ (Tables 3 and 4)
Table 3.Meter Registers
Previous 4 Batches
per meter run are
held in each of the
3n51 registers
METER #1
REGISTERS
METER #2
REGISTERS
METER #3
REGISTERS
METER #4
REGISTERS
3151 (Previous
4 batches.
1=last batch,
4=oldest)
3251 (Previous
4 batches.
1=last batch,
4=oldest
3351 (Previous
4 batches.
1=last batch,
4=oldest)
3451 (Previous
4 batches.
1=last batch,
4=oldest)
SG60/Density @Ref
Temp.
8508
8608
8708
8808
API60/
8519
8619
8719
8819
BS&W
8517
8617
8717
8817
Recalculate & Print
(Edge-Tiggered)
2758
2757
2758
2759
52-0000-0009/Rev C Page 5 of 8
TB-980202C
Recalculating a Previous Batch
within the Flow Computer
Table 4. Station Registers
STATION REGISTERS
Previous 4 Batches for Station are in 3879
(1=last batch, 4=oldest)
3879
SG60/Density @ Ref Temp.
8908
API60/
8919
BS&W
8917
Recalculate & Print (edge-Tiggered)
1798
NOTE: Station registers are available via Modbus Communications. Applies to Version
20/24.74.32
Version 20.74+
NOTE: When recalculating a previous batch and adjusting the gravity of the product using Modbus
transactions, you must write both updated SG60 and equivalent API60 gravity values before
sending the ‘Recalculate and Print’ command. API/SG conversion equations as follows:

API60 = (141.5/SG60) -131.5

SG60 = 141.5 / (API60 + 131.5)
Modbus Communication Summary
NOTE: Setting these registers via Variable Statement is not allowed and will not produce the expected
results.
The flow computer retains data for the last four (4) completed batches. Only one (1) set of this data can
be accessed at a time. Pointer registers, 3151 Meter Run #1, 3251 Meter Run #2, 3351 Meter Run #3,
3451 Meter Run #4n and 3879 for Meter Station are used to determine what set of batch data will be
accessed. API60/SG60 and S&W data can be adjusted and the batch recalculated by writing a ‘1’ to
points, 2756 for Meter Run #1, 2757 for Meter Run #2, 2758 for Meter Run #3, 2759 for Meter Run #4
and 1798 for Meter Station.
Meter “n” Batch Recalculation
Applies to Versions 22.74+ and 26.74+ (Tables 5 and 6)
NOTE: Always write to 3n51 or 3879 to specify the number of retroactive bbls/m3 to recalculate
before writing to any of the above Modbus Points.
Table 5. Meter Registers
Previous 4 Batches
per meter run are
held in each of the
3n51 registers
METER #1
REGISTERS
METER #2
REGISTERS
METER #3
REGISTERS
METER #4
REGISTERS
3134 (Previous
4 batches.
1=last batch,
4=oldest)
3234 (Previous
4 batches.
1=last batch,
4=oldest
3334 (Previous
4 batches.
1=last batch,
4=oldest)
3434 (Previous
4 batches.
1=last batch,
4=oldest)
SG60/Density @Ref
Temp.
8508
8608
8708
8808
API60/
8515
8615
8715
8815
BS&W
8514
8614
8714
8814
Recalculate & Print
(Edge-Tiggered)
1756
1757
1758
1759
52-0000-0009/Rev C Page 6 of 8
TB-980202C
Recalculating a Previous Batch
within the Flow Computer
Table 6. Station Registers
STATION REGISTERS
Previous 4 Batches for Station are in 3879
(1=last batch, 4=oldest)
3879
SG60/Density @ Ref Temp.
N/A
API60
N/A
BS&W
N/A
Recalculate & Print (edge-Tiggered)
1798
Version 22.74+
NOTE: When recalculating a previous batch and adjusting the gravity of the product using Modbus
transactions, you must write both updated SG60 and equivalent API60 gravity values before
sending the ‘Recalculate and Print’ command. API/SG conversion equations as follows:

API60 = (141.5/SG60) -131.5

SG60 = 141.5 / (API60 + 131.5)
Modbus Communication Summary
NOTE: Setting these registers via Variable Statements is not allowed and will not produce the expected
results.
The flow computer retains data for the last four (4) completed batches. Only one (1) set of this data can
be accessed at a time. Pointer registers, 3134 Meter Run #1, 3234 Meter Run #2, 3334 Meter Run #3,
3434 Meter Run #4n and 3879 for Meter Station are used to determine what set of batch data will be
accessed. API60/SG60 and S&W data can be adjusted and the batch recalculated by writing a ‘1’ to
points, 1756 for Meter Run #1, 1757 for Meter Run #2, 1758 for Meter Run #3, 1759 for Meter Run #4
and 1798 for Meter Station.
52-0000-0009/Rev C Page 7 of 8
TB-980202C
Recalculating a Previous Batch
within the Flow Computer
DOCUMENT REVISION HISTORY
DOCUMENT INITIAL RELEASE DATE...................................................... 23-Feb-1998
REVISION
A
B
C
DATE
23-Feb-1998
No Record
03-June-2009
PURPOSE / CHANGE REQUEST
Maintained on the Web - Initial release
Maintained on the Web
DCR 090040
52-0000-0009/Rev C Page 8 of 8
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