Section 2: Description of MicroTSG
SBE 45
12
Baud Rate, Cable Length, Power, and Data Transmission Rate
Baud Rate, Cable Length, and Data Transmission Rate
The rate that data can be transmitted from the MicroTSG is dependent on the
amount of data to be transmitted per scan and the serial data baud rate:
Time to transmit data =
(number of characters * 10 bits/character) / baud rate
where
Number of characters is dependent on the included data and output
format (see
Data Output Format
in
Section 4: Setting Up MicroTSG
).
Add 2 to the number of characters shown in the output format, to
account for the carriage return and line feed at the end of each scan.
Include decimal points, commas, and spaces when counting the
number of characters.
Note that the MicroTSG transmits data
after
it has completed the previous
sample and
before
it starts the next sample. See
Sample Timing
above for
information on sampling time.
The length of cable that the MicroTSG can drive to transmit real-time data is
also dependent on the baud rate. The allowable combinations are:
Maximum Cable Length (meters)
Maximum Baud
800 1200
400 2400
200
4800 (factory set default)
100 9600
50 19200
25 38400
Notes:
•
Baud rate is set with
Baud=
.
•
Real-time output rate is set
with
Interval=
.
•
Output format is set with
OutputCond=
,
OutputSal=
, and
OutputSV=
.
See
Command Descriptions
in
Section 4: Setting Up MicroTSG
for
command details.
Example
–
What is the minimum transmission time over 100 m of cable with
OutputCond=Y
,
OutputSal=Y
,
OutputSV=Y
, and
OutputFormat=0
?
With 100 meters of cable, the MicroTSG requires a baud rate of 9600 or less.
Number of characters (from
Data Output Format
in
Section 4: Setting Up MicroTSG
) =
8 (T) + 2 (comma & space) + 8 (C) + 2 (comma & space) + 8 (salinity) + 2 (comma & space) + 8 (sound velocity)
+ 2 (carriage return & line feed) = 40
Time required to transmit data = (40 characters * 10 bits/character) / 9600 = 0.042 seconds = 42 msec
What is the minimum
total
time required per sample (
Interval=
), if averaging 4 measurements/sample (
NCycles=4
)
and operating in Autonomous Sampling Mode?
In Autonomous mode, time to acquire T and C (from
Sample Timing
above)
= (
NCycles
* 0.1336) + 0.287 = (4 * 0.1336) + 0.287 = 0.82 seconds
Total sampling time
= time to acquire T and C + time to compute parameters (from
Sample Timing
above) + time to transmit data
= 0.82 + (.0088 + .0154 + .083 + .035) + .042 = 1.00 second
Therefore, set
Interval=1
, transmitting 1 sample every second.
17
Содержание SBE 45 MicroTSG
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Страница 98: ...CALIBRATION SHEETS SBE 45 Temperature Calibration S N 0402 1 SBE 45 Conductivity Calibration S N 0402 2 95 ...
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