Mindeo ES4200, Руководство пользователя

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82
4-7 START_DECODE
Description: Ask the scanner to attempt to decode a barcode
Packet Format
Length Opcode Status Checksum
0x03
0x53
(‘S’)
Field Descriptions
Table 4-9 Field Descriptions
Field Name Format Size Description
Length
Length of message (not including
checksum).
1 Byte Length Field
Opcode 0x53 1 Byte Identifies this opcode type.
Status
Bit 0：Retransmit
Bit 1-6：Unused
Bit 7: Command source
1 Byte
Bit 0: Identifies the transmission status.
Bit 7: 1, Command is from the host.
0, Command is from the scanner
All unused bits must be set to 0.
Checksum
2's complement sum of message
contents excluding checksum.
2 Bytes Checksum of message.
This command asks the scanner to start a scan and a decode session. The decode session ends with a
successful decode, or a scan session time-out, or a STOP_DECODE command.
For example:
Length Opcode Status Checksum
0x03 0x53 0x80 0xFF 0x2A
Host Requirements
None.
Scanner Requirements
The scanner must decode a barcode in any mode, when received the START_DECODE command.