DMU380SA Series
User’s Manual
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Doc# 7430-0026 Rev. 01
Page 46
6
Programming Guide
The DMU380SA Series contains a number of different products which have different
measurement capabilities. Depending on the model you purchased, various commands
and output modes are supported. However, all models support a common packet structure
that includes both command or input data packets (data sent to the DMU380SA Series)
and measurement output or response packet formats (data sent from the DMU380SA
Series). This section of the manual explains these packet formats as well as the supported
commands. NAV-VIEW also features a number of tools that can help a user understand
the packet types available and the information contained within the packets. This section
of the manual assumes that the user is familiar with ANSI C programming language and
data type conventions.
For an example of the code required to parse input data packets, please see refer to
Appendix C.
For qualified commercial OEM users, a source code license of NAV-VIEW can be made
available under certain conditions. Please contact your MEMSIC representative for more
information.
General Settings
6.1
The serial port settings are RS232 with 1 start bit, 8 data bits, no parity bit, 1 stop bit, and
no flow control. Standard baud rates supported are: 9600, 19200, 38400, and 57600.
Common definitions include:
A word is defined to be 2 bytes or 16 bits.
All communications to and from the unit are packets that start with a single word
alternating bit preamble 0x5555. This is the ASCII string
“UU”.
All multiple byte values are transmitted Big Endian (Most Significant Byte First).
All communication packets end with a single word CRC (2 bytes).
CRC’s are
calculated on all packet bytes excluding the preamble and CRC itself. Input
packets with i
ncorrect CRC’s will be ignored.
Each complete communication packet must be transmitted to the DMU380SA
Series inertial system within a 4 second period.
Number Formats
6.2
Number Format Conventions include:
0x as a prefix to hexadecimal values
single quotes
(‘’) to delimit ASCII characters
no prefix or delimiters to specify decimal values.
Table 20 defines number formats:
Table 20.
Number Formats
Descriptor
Description
Size (bytes)
Comment
Range
U1
Unsigned Char
1
0 to 255
U2
Unsigned Short
2
0 to 65535
U4
Unsigned Int
4
0 to 2^32-1
