Mindeo ES4200, Руководство пользователя

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88
Field Name Format Size Description
ending with ‘\0’,1 to 23 bytes.
Parameter
Value
Variable 1 to 23 bytes
… Variable
Next parameter setting（option code，data
type，parameter value）….
Checksum
2's complement sum of
message contents
excluding checksum.
2 Bytes Checksum of message.
This message is sent by the scanner in response to the PARAM_REQUEST message, or by the host to
change the scanner’s parameter values.
Example: to set parameter Flow control to be None (see section “
3-2 RS-232 interface
”).
Length Opcode Status Parameter code Data type
Parameter
value
Checksum
0x0A 0x23 0xC0
0x30 0x33 0x30 0x31
(‘0’ ‘3’ ‘0’ ‘1’)
0x44
‘D’
0x30 0x30
(‘0’ ‘0’)
0xFD 0xAB
Host Requirements
The host transmits this message to change the scanner’s parameters. Be sure the Change Type bit (bit
6 of the Status byte) in the Status field is set as desired.
Scanner Requirements
When the scanner receives a PARAM_SEND, it interprets and stores the parameters, then ACKs
the command (if ACK/NAK handshaking is enabled). These parameters are stored permanently
only if the Change Type (bit 6 of the Status byte) is set to 1. Frequent permanent changes are not
recommended due to the limited write-cycles of flash memory. If bit 6 is set to 0 the changes are
temporary, and are lost when the engine is powered down.
If the scanner changes the parameter, it issues the requested beep sequence and stores the
requested parameter values.
Figure 4-1 Host demands scanner to change parameter
The scanner issues a PARAM_SEND in response to a PARAM_REQUEST from the host. It
responds to the PARAM_REQUEST message by sending all supported parameter values. No value
Host Engine
(1)
PARAM_SEND
(2)
Store parameters and ACK