Opticon XPT 3125 Universal menubook - Manual (Page 18)

Interf
ace
2
OPTICON Universal menu book
U11
2.1.3. Handshaking
Data flow control is available using either
hardware (Modem, Busy/Ready) or software
(XON/XOFF). In addition, an optional
acknowledgement control is available (ACK/
NAK with or without error response). Flow
control may be combined with
acknowledgement control. The RS232 voltage
levels employed by most readers for
transmission are either -10V (OFF) or +10V
(ON).
1. No handshake:
Does not employ any handshaking: data is
transmitted regardless of the control signals.
This option will undo any handshake and flow
control options selected.
2. Busy/ready:
The reader's RTS is ON as soon as the power
is supplied to the reader and will stay ON while
the reader can receive data from the host. The
host will keep the reader's CTS ON while it is
ready to receive data from the reader. While
CTS is ON the reader is able to transmit data.
The reader will abort transmission with an error
indication of the buzzer when the CTS is not
ON within a certain configurable period. The
reader may drop RTS to OFF during
transmission if it can not receive data
simultaneously. See figure 2.04.
3. Modem mode:
The reader's RTS is OFF as soon as power is
supplied to the reader. The reader will turn RTS
ON when it wants to transmit data to the host.
The host should respond by putting CTS ON
when it is ready to receive data. While CTS is
ON the reader is allowed to transmit data.
When all data has been transmitted, the reader
will turn RTS OFF. In response, the host should
turn OFF the reader's CTS. If, while RTS is ON,
the CTS line is not ON for a certain
configurable period, the reader will terminate
the transmission with an error indication of the
buzzer. See figure 2.05.
4. XON/XOFF:
The reader sends data until an XOFF (ASCII
DC3, Hex 13) character is received from the
host. Only when the reader receives an XON
(ASCII DC1, Hex 11) character, the reader
continues to send its data.
5. ACK/NAK:
After data has been transmitted, the reader
expects to receive one of the following
responses from the host:
Response: "ACK" (ASCII: Hex Ø6)
Action: The reader completes transmission with
the good-read buzzer.
Response: "NAK" (ASCII: Hex 15)
Action: The reader sends the data again.
Response: "DC1" (ASCII: Hex 11)
Action: The reader completes transmission
without a good-read or error buzzer.
RTS
CTS
TxD
ON
OFF
ON
OFF
ON
OFF
Fig. 2.04. HandShaking
Busy/ready
RTS
CTS
TxD
ON
OFF
ON
OFF
ON
OFF
Fig. 2.05. HandShaking
Modem mode