Liquid Controls SP2900 - Manual (Page 21)

IRREGULAR SHAPE VESSEL APPLICATION NOTE;
MEASURE VOLUME IN IRREGULAR SHAPED VESSELS
WITH 16-POINT LINEARIZATION OPTION.
In the past it was difficult to calculate the volume of liquid
and set up the equation or computer model to display the
volume in containers with odd shapes. It usually required
that a special electronic memory be made for each con-
tainer.
The “16-Point” option allows a simple was to program the
unit to display correct volume with resolution to 10,000
parts.
all that is needed is the analog signal from a weight or level
transducer (4 to 20 or 0 to 20mA, 0 to 5, 1 to 5, 0 to 10
VDC).
The easiest way to set the 16 points is to use the “Test”
mode while filling the vessel. In this “Test” mode the unit
converts the analog signal to a 1 to 10,000 base frequency
reading.
Record the “Test” frequency reading in a column next to
actual amount put into the vessel. Choose 16 points where
there is a significant ratio change between the frequency
reading and the actual volume. Divide the “Test” frequency
by the actual volume to determine the the point K-Factor to
be entered with the “test” frequency. Simply key in these
point frequencies and K-Factors in order of ascending
frequencies. Volumes between the 16 points entered will be
interpolated from a K-Factor line slope generated from the
closest 2 points entered.
Once the “16-Point” frequencies and K-Factors are entered,
set the unit to “Second” reading of rate to display actual
volume in the vessel. Disregard the counter readings.
Two separate control relays can be set to activate at
different volume for monitoring or dispensing applications.
An optional 4 to 20mA output of the corrected volume can
be supplied to drive a strip chart recorder, remote meter or
other equipment.
CONCLUSION
This manual has attempted to cover all aspects of opera-
tion of the unit. It is written to cover most anticipated
problems and misunderstandings. if some questions still
arise or you feel some improvements can be made to this
manual, please feel free to contact your local representa-
tive.
We hope you will be pleased with our product. If you have
any questions concerning our warranty, repair, modification
or returned goods process, please contact your local
distributor.
COMMUNICATION FOR 16 POINT
When 16-Point option is supplied with either RS232 or
RS422 option, data can be read and changed as explained
under Communication Section of the manual.
Codes to address 16-point data: (F=frequency; K=K-Factor;
A to P = Point number 1 to 16)
FA = Frequency for A (Point 1)
KA = K-Factor for A (Point 1)
FB = Frequency for B (Point 2)
KB = K-Factor for B (Point 2)
- - = (Use of letters A to P for Points 1 to 16)
FP = Frequency for P (Point 16)
KP = K-Factor for P (Point 16)
To request a transmit of data, send a code for information
desired. To change data, send the desired address code
followed by a space and the new number desired.
Sample Code request and response:
Transmit from terminal Receive from unit
(S) = Space
Example A:
D13(S) (unit #13 activated)
Device #13
FA(S)0(S)KA(S)123 (ENTER) FA 0 KA 123
(Frequency for A (Point 1) is set (Unit echoes back
to 0, K-Factor for A (Point 1) command as sent)
is set to 123)
Example B:
D11(S) (unit #11 is activated)
Device #11
FC(S)500(S)KC(S)305(S) FC 500 KC 305
FC(S)KC(S)(ENTER) FC KC
(Frequency for C (Point 3) is set (Unit echoes back
to 500, K-Factor for C (Point 3) command as sent)
is set to 305,
Frequency of C (Point 3) is
500
sent, K-Factor of C (Point 3) 305
is sent. (Unit transmits
frequency and
K-Factor data for
C (Point 3).
CAUTION:
1) Frequency speed must increase with ascending point
numbers. A bad sequence can be entered over the serial
part. Unit will use calculated K-Factor based on first fre-
quency match found, which may be wrong. Check by
requesting a transmit of all frequency points used: FA FB
FC FD to F_ to insure ascending sequence is entered or
enter “POINT 00” on front keypad and unit displays “BAD
SEQ” if there are errors.
2) After device is activated, there must be a delay to allow
“Device #--” to be transmitted by the device before new
commands are sent to the unit.
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