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glossary:glossary_r [2017/02/16 10:10]
WortingUK [Raspberry Pi]
glossary:glossary_r [2019/11/12 01:51]
Bob Vetterlein [RFID]
Line 90: Line 90:
 [[http://​​wiki/​RFID|Wikipedea article]]\\ ​ [[http://​​wiki/​RFID|Wikipedea article]]\\ ​
 [[glossary:​thomasrfid|MERG Demonstration]]\\ ​ [[glossary:​thomasrfid|MERG Demonstration]]\\ ​
 +**MERG RFID systems**\\ ​
 +The tags generally used in MERG RFID systems have a 40 bit ID number, that is 5 bytes, when transmitted there is then a sixth byte added which is a checksum for data integrity. The tag readers transmit the data over a serial link using [[glossary_h#​ascii_hex|ASCII Hex]]. The start of a message is STX <​0x02>​ this is followed by the 12 ASCII Hex characters of the data plus checksum, some readers then send LF <​0x0A>​ CR <​0x0D>,​ and finally ETX <​0x03>​. This makes a message of either 14 or 16 bytes in total.\\ ​
 +The MERG Concentrator replaces the STX with a reader identification letter, A to H or I to P. For CBUS the incoming data is converted back to its original 5 bytes and checked against the checksum. These 5 bytes are then transmitted as bytes 3 to 7 of an 8 byte message. <​Opcode><​DN/​NN Hi><​DN/​NN Lo><​data0><​data1><​data2><​data3><​data4>​
 ===== Risk assessment ====== ===== Risk assessment ======
glossary/glossary_r.txt ยท Last modified: 2020/03/12 05:27 by michael_smith