User's Manual

Product Manual - RFID Reader LF60C SoliD 66
Chapter 7
Operation
Message block
structure
SECS message blocks have the following form:
The operation of all communication functions above the block transfer protocol is
linked in information contained in a 10-byte data element, called the header.
The header is always the first 10 bytes of every block sent by the block transfer
protocol.
The length includes all bytes sent after the length byte, excluding the two
checksum bytes. The maximum block length allowed by SECS-I is 254 bytes and
the minimum is 10 bytes.
The reverse bit (R bit) signifies the direction of a message. The R-bit (msb) is
set to 0 for messages to the equipment and to 1 for messages to the host.
The device ID is a definite number to contact the reader.
The device ID consists of the 8-bit gateway ID (bit 0 - bit 7), which is identical
with the last two characters of the reader's serial number, and a 5-bit fixed reader
number
(bit 8 - bit 14 = 0x01).
Of course, the ID can be changed within the valid scope.
Byte msb Description
Length 0 Length without checksum, 10 - 254
1 R Upper device ID (Reader ID)
2 Lower device ID (Gateway ID)
3 W Upper message ID (Stream)
4 Lower message ID (Function)
5 E Upper block number
6 Lower block number
System
bytes
7 System byte 1
8 System byte 2
9 System byte 3
10 System byte 4
Text 11 - 254 message text, user data
Check sum 255, 256 16-bit unsigned checksum