User's Manual

RS232-Transponder Reader
(SECS1-Protocol), Release 0.3 Draft Page 35 of 91
2000-09-29
ID: ID000093
8.1 SECS-1 Implementation
This message set describes the communication between a SECS-1 reader and a
host. The communication between the host and the transponder-reader happens
via a RS232 interface (SECS-1).
8.1.1 Character structure
Data will be transmitted or received in a serial bit stream of 10 bits per character at
one of the specified data rates. The standard character has one start bit(0),
8 data bits and one stop bit(1). All bit transmissions are of the same duration.
SECS1 performs no parity or other verification of the individual bytes.
8.1.2 Block Transfer Protocol
The gateway will use an interpretation of SECS-1 by a serial transport layer. The
following are some points to note about this implementation.
1. Master-Slave
The host connects to the reader. When there is contention the host "gives in" (i.e.
receives before sending).
In the communication course the reader takes on the part of the master and the
host the part of the slave!
2. Control Characters
The four standard handshake codes used in the block transfer protocol are shown
in the table.
<ENQ> 0x05 Request to Send
<EOT> 0x04 Ready to Receive
<ACK> 0x06 Correct Reception
<NAK> 0x15 Incorrect Reception