User's Manual

Brooks Automation
260301 Revision A 55
ATR60LF RFID Reader CAN Bus 7 Operation
Product Manual 7.5 Operation of the SECS Protocol
Block transfer
protocol
The drawing below illustrates some simple message interactions between
the host and the equipment. The figure shows the possible handshake
sequence 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.
When both the host and the equipment try to send at the same time, the
host must cancel its inquiry, because the host is working in slave mode. It
must first receive the equipment message, because the reader is the
master. Only then can the host send its message.
For more detailed information about all possible cases, see SEMI E4.
(SEMI Equipment Communication Standard 1 Message Transfer SECS-I)