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IV Communication Protocol
The protocol defines the data exchanging format when R503 series communicates with upper
computer. The protocol and instruction sets apples for both UART communication mode.
Baud rate 57600, data bit 8, stop bit 1, parity bit none.
Data package format
When communicating, the transferring and receiving of command/data/result are all wrapped in
data package format. For multi-bytes, the high byte precedes the low byte (for example, a 2 bytes
00 06 indicates 0006, not 0600).
Data package format
Header
Adder
Package
identifier
Package
length
Package content
(instruction/data/Parameter
）
Checksum
Definition of Data package
Name
Symbol
Length
Description
Header
Start
2 bytes Fixed value of 0xEF01; High byte transferred first.
Adder
ADDER
4 bytes
Default value is 0xFFFFFFFF, which can be modified by
command. High byte transferred first and at wrong adder value,
module will reject to transfer.
Package
identifier
PID
1 byte
01H
Command packet;
02H
Data packet; Data packet shall not appear alone in
executing process, must follow command packet or
acknowledge packet.
07H
Acknowledge packet;
08H
End of Data packet.
Package
length
LENGTH
2 bytes
Refers to the length of package content (command packets and
data packets) plus the length of Checksum( 2 bytes). Unit is
byte. Max length is 256 bytes. And high byte is transferred first.
Package
contents
DATA
－
It can be commands, data, command
’
s parameters,
acknowledge result, etc. (fingerprint character value, template
are all deemed as data);
Checksum
SUM
2 bytes
The arithmetic sum of package identifier, package length and
all package contents. Overflowing bits are omitted. high byte is
transferred first.