DMU380SA Series
User’s Manual
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Doc# 7430-0026 Rev.01
Page 47
I2
Signed Short
2
2’s Complement
-2^15 to 2^15-1
I2*
Signed Short
2
Shifted 2’s Complement
Shifted to specified
range
I4
Signed Int
4
2’s Complement
-2^31 to 2^31-1
F4
Floating Point
4
IEEE754 Single
Precision
-1*2^127 to 2^127
SN
String
N
ASCII
Packet Format
6.3
All of the Input and Output packets, except the Ping command, conform to the following
structure:
0x5555
<2-byte packet type
(U2)>
<payload byte-length
(U1)>
<variable length
payload>
<2-byte CRC (U2)>
The Ping Command does not require a CRC, so a DMU380SA Series unit can be pinged
from a terminal emulator. To Ping a DMU380SA Series unit, type the ASCII string
‘UUPK’.
If properly connected, the DMU380SA Series
unit will respond with ‘PK’.
All
other communications with the DMU380SA Series unit require the 2-byte CRC. {Note:
A DMU380SA Series unit will also respond to a ping command using the full packet
formation with payload 0 and correctly calculated CRC. Example: 0x5555504B009ef4 }.
6.3.1
Packet Header
The packet header is always the bit pattern 0x5555.
6.3.2
Packet Type
The packet type is always two bytes long in unsigned short integer format. Most input
and output packet types can be interpreted as a pair of ASCII characters. As a semantic
aid consider the following single character acronyms:
P = packet
F = fields
Refers to Fields which are settings or data contained in the unit
E = EEPROM
Refers to factory data stored in EEPROM
R = read
Reads default non-volatile fields
G = get
Gets current volatile fields or settings
W = write
Writes default non-volatile fields. These fields are stored in non-volatile memory
and determine the unit’s behavior on power up.
Modifying default fields take
effect on the next power up and thereafter.
S = set
