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SE-923 Scan Engine Integration Guide
Figure 6-1 show the general packet format for SSI messages, and Table 6-2 lists the
descriptions of fields that occur in all messages. These descriptions are repeated for each
Opcode in the SSI message formats section. For messages that utilize the "Data" field, the
specific type of data is shown in that field.
Length
Opcode
Field Name
Length
1 Byte
Opcode
1 Byte
Message Source
1 Byte
Status
Bit 0
Bit 1
Bit 2
Bit 3
Bits 4 - 7
Data...
Variable number of
bytes
Checksum
2 Bytes
Note: The checksum is a 2 byte checksum and must be sent as HIGH BYTE followed by LOW
BYTE.
6-4
Message Source
Figure 6-1. General Packet Format
Table 6-2. Field Descriptions
Format
Length
See Table 6-1 for details. Identifies the type of packet
0 = Decoder
04 = Host
Retransmit
Reserved
Reserved
Change Type
(applies to parameters)
See individual sections
for details.
2's complement sum of
message contents
excluding checksum.
Status
Sub-Field
Length of message not
including the check sum bytes.
Maximum value is 0xFF.
data being sent.
Identifies where the message is
coming from.
0 = First time packet is sent
1 = Subsequent transmission
attempts
Always set to zero
Always set to zero
0 = Temporary change
1 = Permanent change
Unused bits must be set to 0.
Checksum of message
formatted as HIGH BYTE
LOW BYTE
Data
Checksum
Meaning
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