Campbell Scientific ST-20 Argos Satellite Transmitter - Manual (Page 7)

ST-20 Argos Satellite Transmitter
1.3 Data Buffers
The ST-20 has 8 internal data buffers. Before a data buffer can be used, a valid
Argos ID number, repetition rate and frequency must be assigned to the buffer.
The Argos ID numbers must be entered as a decimal and a Hexadecimal
number. The ST-20 uses the Hexadecimal format to determine if the ID is a 28
bit ID number. When using 28 bit ID numbers, 31 bytes of data can be stored
in the buffer. When using 20 bit ID numbers, 32 bytes of data can be stored in
the buffer. The data buffers are numbered 0 through 7, with 7 being reserved
for other uses.
Data buffer setup can be done by the factory or under datalogger control. The
factory settings are stored in non-volatile memory. Settings that have been
changed by the datalogger are erased when the ST-20 resets.
1.4 Multiple Argos ID Numbers
The use of multiple ID numbers can significantly change how the datalogger is
programmed. When multiple ID numbers are used, the ArgosTransmit()
function works best. When ArgosTransmit() is executed, the contents of the
specified data buffer are transmitted once. ArgosTransmit() gives full control
of timing of transmissions to the datalogger programmer. Special care must be
taken to avoid transmitting too often. The programmed repetition period must
match the System Use Agreement between the user and Service Argos.
1.5 One Argos ID Number
The ArgosDataRepeat() function is most useful when only one Argos ID
number is used. It does not matter how many data buffers use the same ID.
ArgosDataRepeat() allows the selection of which data buffers will be
transmitted, and at what repetition period. When ArgosDataRepeat() is used to
start data transmission, the ST-20 will wait one repetition period between each
transmission. One buffer is transmitted each transmission, regardless of how
many buffers have been enabled. The maximum number of transmissions that
can be scheduled with ArgosDataRepeat() is 255.
2. Datalogger Programming
There are 5 programming instructions available for use with the ST-20 Argos
PTT: ArgosSetup, ArgosData, ArgosDataRepeat, ArgosTransmit, and
ArgosError. The use of ArgosSetup is optional. ArgosData and
ArgosDataRepeat are used to enable transmission of data. More advanced
applications can use ArgosTransmit. If the setup parameters of the PTT need
to be changed, use ArgosSetup first. The setups are maintained in memory
until the PTT resets. Once the setup parameters are set, use ArgosData
followed by ArgosAutoRepeat. Data in a buffer is saved until the PTT resets
or is overwritten by another occurrence of ArgosData. If either the
ArgosDataRepeat or ArgosTransmit instruction tries to use a data buffer that
has not been setup, the instruction will fail.
2.1 Argos Setup
ArgosSetup (Result Code, Buffer Number, Decimal ID, Hexadecimal ID,
Frequency)
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