Mindeo ES4200, Руководство пользователя

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4-10 PARAM_REQUEST
Description: Request values of selected parameters
Packet Format
Length Opcode Status
Option code
Checksum
0x3F
(‘?’)
Field Descriptions
Table 4-12 Field Descriptions
Field Name Format Size Description
Length
Length of message (not including
checksum).
1 Byte Length Field
Opcode 0x3F 1 Byte Identifies this opcode type.
Status
Bit 0：Retransmit
Bit 1-5：Query property of the
parameter
Bit 6：Unused
Bit 7: Command source
1 Byte
Bit 0: Identifies the transmission status.
Bit1-5：Control querying the property of
parameter
0, Query maximum value of the
parameter
1, Query minimum value of the
parameter
2, Query permanent setting value of the
parameter
3, Query temporary setting value of the
parameter
4, Query the default value of the
parameter
5-15,Reserved.
Bit 6: Reserved to be 0.
Bit 7: 1, Command is from the host.
Option
code
ASCII value of the option code Variable
Each option code has 4 bytes, the
scanner can query several parameters.
Parameter 1, Parameter 2…
Checksum
2's complement sum of message
contents excluding checksum.
2 Bytes Checksum of message.
The host uses this message to request selected parameters from the scanner.
Host Requirements
The host requests the scanner’s current values for specific parameters by listing the parameter codes in
the Request Data field. If the host asks for a parameter value which is not supported by the scanner, the