User's Manual

OPERATION 5

HF5x Transponder Reader (SECS1-Protocol), Release 1.4

5.3 SECS-1 Implementation

This message set describes the communication between a SECS-1

reader and a host. The host and the transponder reader communicate

via an RS232 interface (SECS-1).

5.3.1 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.

5.3.2 Block Transfer Protocol

The reader will use an interpretation of SECS-1 by a serial transport

layer. The following are some points to note about this

implementation.

5.3.2.1 Master Slave

The host connects to the reader. If there is contention, the host “gives

in” (i.e. receives before sending).

In the course of communication, the reader takes on the role of the

master, and the host takes on the role of the slave.

5.3.2.2 Control Characters

The four standard handshake codes used in the block transfer protocol

are displayed in the table below.

<ENQ>

0x05 Request to Send

<EOT>

0x04 Ready to Receive

<ACK>

0x06 Correct Reception

<NAK>

0x15 Incorrect Reception