System information

Section 2. Protocols and Packet Types
2-21
Table definitions may be sent from the datalogger to the application prior to the
first transmission of a one-way data message and periodically thereafter. Use
the table definitions to calculate the table signatures for each table in the same
manner as the standard data collection process. The table definition signature
is always included in the one-way data message as an independent verification
that the table definitions have not changed since they were last received. Since
these one-way data messages exist outside of any transaction, the transaction
number will always be zero.
One-Way Table Definition Message Body (MsgType 0x20):
Name Type Description
MsgType Byte Message type code (0x20)
TranNbr Byte Transaction number
TableNbr UInt2 Table number
TableName ASCIIZ Table name
TableSize UInt4 Number of records allocated in the datalogger
for this table
TimeType Byte Data type code of the Time Tag field
TblTimeInto Nsec “Time Into” part of the “Time Into Interval”
for the table interval
{ ReadOnly bit 7 0: Read/Write
1: Read only
FieldType bits 6..0 Data type of the field
FieldName ASCIIZ Name of the field within the table
{ AliasName } ASCIIZ Alias or “FieldName” assigned to the elements
within this field. Currently not used.
(0) Byte Alias names list terminator
Processing ASCIIZ Designates the type of processing and
processing parameters used to generate this
field (i.e. “Max”, “Min”, “Avg”, “WndVec”,
etc.). This field provides information
necessary to display data, for example, if this
field were a histogram, the parameters might
include the name, units, and dimensions of the
other axis for graphing.
Units ASCIIZ Field units
Description ASCIIZ [0..80] Description of the field
BegIdx UInt4 Beginning index. The array index number that
for the first element of the array (1 by default
or if not an array).
Dimension UInt4 Array dimension of the whole array (set to 1 if
not an array)
{ SubDim } UInt4 Sub-dimension of a multidimensional array
(0) } UInt4 Sub-dimension list terminator
(0) Byte Field list terminator