SFG R303A Series, Руководство пользователя, Страница: 8 / 24

The new modified password is stored in Flash and remains at power off.
Module address
Each module has an identifying address. When communicating with upper computer, each
instruction/data is transferred in data package form, which contains the address item. Module
system only responds to data package whose address item value is the same with its identifying
address.
The address length is 4 bytes, and its default factory value is 0xFFFFFFFF. User may modify the
address via instruction SetAdder. The new modified address remains at power off.
Random number generator
Module integrates a hardware 32-bit random number generator (RNG) (without seed). Via
instruction GetRandomCode , system will generate a random number and upload it.
V Communication Protocol
The protocol defines the data exchanging format when ZFM-20 series communicates with upper
computer. The protocol and instruction sets apples for both UART and USB communication mode.
For PC, USB interface is strongly recommended to improve the exchanging speed, especially in
fingerprint scanning device.
5.1
Data package format
When communicating, the transferring and receiving of command/data/result are all wrapped in
data package format.
Data package format
Header Adder Package
identifier
Package
length
Package content
(instuction/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.
01H Command packet;
02H
Data packet; Data packet shall not appear alone in
executing processs, must follow command packet or
acknowledge packet.
Package
identifier
PID 1 byte
07H Acknowledge packet;
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