5-12 PARAM_REQUEST
Description: Request values of selected parameters
Packet Format
(not including checksum).
Identifies this opcode type.
Bit 0: Identifies transmit status
Bit 5-1: Unused
Bit 6: Unused
Bit 7: Command source
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.
Parameter1, Parameter2, …
Each parameter code has 4 bytes; Host
can request several parameters at the
same time.
2's complement sum of message contents
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:
the PARAM_SEND responded by scanner is as following:
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
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