Trimble Outdoors SK8 - Manual (Page 149)

Lassen-SK8 Embedded GPS Module C-3
Trimble ASCII Interface Protocol (TAIP)
C.1.3 Message Identifier
A unique two character message identifier consisting of alphabetical characters is used to
identify type messages. For example: PR for Protocol or VR for Version Number.
C.1.4 Data String
The format and length of a data string is dictated by the message qualifier and the message
identifier. The data string may contain any printable ASCII character with the exception of
the >, <, and ; characters. Detailed descriptions of each message format are provided in the
specific message sections of this Appendix. Most messages are length sensitive and unless
otherwise specified, field separators, including spaces are not used.
C.1.5 Vehicle ID
A vehicle identification(ID) may optionally be used in all the communications with the
sensor. Each sensor in the fleet may be assigned a four character alpha-numeric ID and be
forced to output that ID in all messages. The default is: ID set to 0000 and the ID Flag set
to F (false).
The sensor will check all incoming messages for ID. If no ID is specified, the sensor will
accept the message. If the ID is included in messages but does not compare with the ID
previously set, the message will be ignored. This applies even when the ID Flag is turned
off.
C.1.6 Checksum
The checksum field provides for an optional two digit hex checksum value, which is
computed as XOR of all characters from the beginning of the sentence up to and
including the * character. If provided, the checksum is always the last element of the
sentence before the message delimiter. The default mode of operation is to include
checksum in sentences. The use of checksums can help in instances where the
communication channel is noisy.
Example:
The following message to set the vehicle ID flag on includes checksum.
>SRM;ID_FLAG=T;*6F<
The checksum (6F) was generated by XOR'ing the ASCII codes for > and S then XOR'ing
that result with the ASCII code for R and so forth, up to and including the * character.
C.1.7 Message Delimiter
The < character signifies end of a sentence and is used as the message delimiter.