Mindeo FS580, User Manual

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87
5-12 PARAM_REQUEST
Description: Request values of selected parameters
Packet Format
Length Opcode Status
Parameter code
Checksum
0x3F
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: Identifies transmit status
Bit 5-1: Unused
Bit 6: Unused
Bit 7: Command source
1 Byte
Bit 0:
0 = First time packet is sent
1 = Subsequent transmission attempts
Bit 5-1: Reserved
Bit 6: Reserved
Bit 7: always be 1(message is from the
host)
All unused bits recommend to be set to
0.
Request
Data
Parameter1, Parameter2, … Variable
Each parameter code has 4 bytes; Host
can request several parameters at the
same time.
Checksum
2's complement sum of message contents
excluding checksum.
2 Bytes Checksum of message.
The host uses this message to request some specific parameters from the scanner.
For example: the value of scanner parameter “0301” is 01, when host queries value of the parameter
“0301”, the PARAM_REQUEST sent by host is as following:
Length Opcode Status Parameter code Checksum
0x07 0x3F 0x80 0x30 0x33 0x30 0x31 0xFE 0x76
the PARAM_SEND responded by scanner is as following:
Length Opcode Status Parameter code Data type parameter Checksum
0x0A 0x23 0x00 0x30 0x33 0x30 0x31 0x44 0x30 0x31 0xFE 0x6A
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 which is not supported by the scanner, the
scanner responds with NAK.
The scanner’s response to this command is PARAM_SEND, not ACK. Depending on the time-out setting,
and the number of parameters requested, this reply may fall outside the programmable Response delay.
If this occurs, this is not a time-out error. To compensate, increase the Response delay.
Scanner Requirements
When the scanner receives this message, it processes the information by formatting a PARAM_SEND