Trimble Outdoors SK8 - Manual (Page 126)

A-62 Lassen-SK8 Embedded GPS Module
Trimble Standard Interface Protocol
A.18 TSIP Superpackets
Several packets have been added to the core TSIP protocol to provide additional capability
for OEM receivers. In OEM packets
0x 8E and their 0x 8F responses, the first data byte is a
sub-code which indicates the superpacket type. For example, in Packet 0x 8E-15, 15 is the
sub-code that indicates the superpacket type. Therefore the ID code for OEM packets is 2
bytes long followed by the data.
A.18.1 Command Packet 0x8E-15 - Set/Request Datum (not supported with
Firmware 7.52)
This packet allows the user to change the default datum from WGS-84 to one of 180
selected datums or a user-entered custom datum. (However version 7.52 firmware will
only support WGS-84 datum.) The datum is a set of 6 parameters which describe an
ellipsoid to convert the GPS receiver's internal coordinate system of XYZ ECEF into
Latitude, Longitude and Altitude (LLA). This will affect all calculations of LLA in
packets
0x 4A and 0x 84.
The user may wish to change the datum to match coordinates with some other system
(usually a map). Most maps are marked with the datum used and in the US the most
popular datum for maps is NAD-27. The user may also wish to use a datum which is more
optimized for the local shape of the earth in that area. However, these optimized datum are
truly “local” and will provide very different results when used outside of the area for
which they were intended. WGS-84 is an excellent general ellipsoid valid around the
world. See A.3 for information on saving the settings to non-volatile memory.
Byte # Item Type Value Meaning
5 # Stop Bits BYTE 0
2
1 bits for 6-8 data bits
2 bits
6 Flow Control BYTE 0-F OR of bits:
0 = none,
1 = RTS CTS
2 = transmit Xon Xoff
4 = transmit Xany
8 = receive Xon Xoff.
7 Input Protocols BYTE 0-1F OR of bits:
0 = none
1 = TAIP
2 = TSIP
8 = RTCM
8 Output Protocols BYTE 0-1F 0 = none
1 = TAIP
2 = TSIP
4 = NMEA
9 Reserved BYTE 0 None
Table A-71. Report Packet 0xBC Field Descriptions (Continued)