Campbell Scientific TX320 Transmitter - Manual (Page 37)

TX320 Transmitter
7.6.1 Deciding How Much Data will be Transmitted and When
The amount of data that can be transmitted depends on several factors: the
transmit window length, the transmit baud rate, and the data format. The
transmit window limits the time available for data to be sent. The baud rate
determines how fast data is sent. The data format determines how many bytes
are required per data point.
The maximum number of data points that can be sent is estimated with this
formula:
b(a-2)/8c = total number of data points per transmission
Where:
a = window length in seconds
b = baud rate or bits/second; for example, 100, 300, or 1200
c = bytes per data point
Binary data uses 3 bytes per data point.
ASCII data uses 7 bytes per data point.
7.6.2 Deciding What Data Format to Use
The choice of data format effects two areas. First, the data format effects how
much data can be sent in a single transmission. Binary data formats require 3
bytes per data point. ASCII data formats require 7 bytes per data point.
Second, binary data must be decoded after transmission, ASCII does not. The
datalogger formats the data before the data is sent to the TX320. The data
format is chosen with the P126 program instruction.
7.6.3 Managing Data, Writing More Data than Will Be Transmitted
The datalogger has two data storage areas: Final Storage area 1 (FS1) and Final
Storage area 2 (FS2). When data is written to final storage, data is written to
the active final storage area. The active final storage area defaults to FS1 when
the datalogger starts the program table. Program Instruction 80 (P80) is used
to set the active final storage area. When P126 executes, all new data in the
active final storage area is sent to the transmitter. New data is all data that has
been written to the active final storage area since P126 last executed.
Two separate data files can be maintained by managing which final storage
area is active when data is written. The amount of data copied to the
transmitter and the order of data copied to the transmitter can be controlled by
utilizing both final storage areas. If using FS2, datalogger memory must be
allocated to FS2. Final storage area 2 memory can be allocated using Edlog or
the keypad.
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