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Transmission Methods
A block with 700 bytes of user data is to be transmitted. For this purpose, the block is divided into three frames:
1
st
frame:
5A CD 50 02 — 200 bytes of user data follow — P1 P2
2
nd
frame:
5A FF 50 01 — 250 bytes of user data follow — P1 P2
3
rd
frame:
5A FF 50 00 — 250 bytes of user data follow — P1 P2
The receiver can use the frame number of the first frame (here
02) and its length byte to calculate the block size (block
size = frame number * 250 bytes + length byte -5) (here in the example: 2 * 250 bytes + 205 bytes - 5 bytes = 700 bytes),
and reserve an appropriate amount of memory for the data.
User Data
User data are the bytes in a frame that flow into the block transmitted.
Checksum
The checksum is calculated using the polynomial x^16 + x^12 + x^5 + 1 with a pre-initialisation of 0x0000 from the start
code to the last user data byte.
Network Layer
As the KBRP is a point-to-point protocol, there is no network layer.
Transport Layer, Session Layer, Presentation Layer,
Do not exist.
Application Layer
The application layer transmits data blocks from 1 to a maximum of 64000 bytes.
13.2
LLRP Protocol
Based on the TCP communication protocol, the Kathrein RFID reader with the Linux operating system can handle the
so-called
Low Level Reader Protocol (LLRP).
It is a communication interface between an RFID reader and a LLRP-enabled application software standardised by
EPCglobal (
http://www.epcglobalinc.org/standards/llrp
). The default port for LLRP is 5084.
The LLRP protocol is roughly divided into the following parts:
●
Automatic query of the reader functions via the application software
●
Configuration of the reader functions via the application software
●
Triggering of read and write operations on the air interface voa the application software
●
Transfer of the found tag data to the application software
To start the LLRP application, use the
AppManager of the ReaderStart. In the menu, it is possible to load the LLRP pro-
tocol engine by means of
Install App and start it using Start App.
To test the Kathrein reader with the LLRP protocol, it is possible to use the open-source programming tool
Eclipse (IDE).
By means of the so-called
LLRP Commander it is possible to control and operate the reader.
Eclipse (IDE) and LLRP Commander are not part of the Kathrein RFID software.
