Mindeo FS580, Руководство пользователя

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5-1 SCI message formats
The general packet format for SCI message is as following:
Length Opcode Status Data Checksum
Table 5-2 lists the descriptions of fields that occur in all messages. These descriptions are repeated for
each opcode. For messages that use the Data field, the specific type of data is described in that field in
later sections.
Table 5-2 Field descriptions
Field name Format Size Description
Length
Information length
(not including checksum)
1 Byte
Length of message not including the check sum
bytes. Maximum value is 0xFF.
Opcode See Table 5-1 for details 1 Byte Identifies this opcode type.
Status
Bit 0: Identifies transmit status
Bit 5-1: Parameter property
(For PARAM_REQUEST and
PARAM_SEND only.)
Bit 6: Change type(apply to parameter
transmission)
Bit 7: Command source
1 Byte
Bit 0:
0 = First time packet is sent
1 = Subsequent transmission attempts
Bit 5-1:
0=Maximum parameter value
1= Minimum parameter value
2= Permanent parameter value
3= Temporary parameter value
4=Default 0 parameter value
5=Custom default parameter value
6-15=Reserved
Bit 6:
0 = Temporary change
1 = Permanent change
Bit 7:
0=Command is from the scanner
1=Command is from the host
All unused bits recommend to be set to 0.
Data See individual sections for details
Variable
number
of Bytes
Checksum
2’s complement sum of message
contents excluding checksum
2 Bytes
Checksum of message formatted as High-Byte
Low-Byte
Note: The checksum is a 2 byte checksum and must be sent as High-Byte followed by Low-Byte.
Checksum = 0x10000 - Length - Opcode - Status - Data.