User's Manual

RS232-Transponder Reader
(SECS1-Protocol), Release 0.3 Draft Page 38 of 91
2000-09-29
ID: ID000093
4. Block Transfer Protocol
The drawing below illustrates some simple message interactions between the host
and the equipment. The figure shows the handshake sequence possible to acquire
the status of the equipment.
When the host wants to send, it first sends an <ENQ> and then tries to read.
If it receives an <EOT> , it sends its message and then expects an <ACK>.
If it receives an <ENQ>, it puts off sending its message, sends an <EOT> and then
reads the other message.
Sending and receiving via the SECS-1 interface alternate with each other!
ENQ
EOT
Länge
Header
Checksum
Daten
ACK
ENQ
Sender: Empfänger:
T2
T2
T1
T2
T4 (bei mehreren Blöcken)
(HOST / READER) (READER / HOST)