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Quadrus MINI Imager User’s Manual
3-5
Communications
Host Port Protocol
Note: In all protocol modes, the preamble <K141> and postamble <K142> character
strings can be used to frame the decode data, and both are included in calculating the
LRC (Longitudinal Redundancy Check).
Point-to-Point (Standard)
Point-to-Point with RTS/CTS
Point-to-Point with XON/XOFF
Usage:
In general, the point-to-point protocols will work well in most applications.
They require no address and must use RS-232 or RS-422 communications
standards.
Definition:
Protocols define the sequence and format in which information is transferred
between the reader and the host, or in the case of Multidrop, between the
readers and a concentrator.
Serial Cmd:
< K140,protocol
,address
>
Default:
Point-to-Point
Options:
0 = Point-to-Point
1 = Point-to-Point with RTS/CTS
2 = Point-to-Point with XON/XOFF
3 = Point-to-Point with RTS/CTS and XON/XOFF
4 = ACK/NAK
5 = Polling Mode
Usage: Used only with RS-232 or RS-422.
Definition:
Standard Point-to-Point requires no address and sends the data to the
host whenever it is available, without a request or handshake from the host.
Serial Cmd:
< K140,0 >
Usage:
A reader initiates a data transfer with an RTS (request-to-send) transmission.
The host, when ready, responds with a CTS (clear-to-send) and the data is
transmitted. RTS and CTS signals are transmitted over two dedicated wires
as defined in the RS-232 standard.
Used only with RS-232.
Definition:
Point-to-Point with RTS/CTS (request-to-send/clear-to-send) is a simple
hardware handshake protocol that allows a reader to initiate data transfers
to the host.
Serial Cmd:
< K140,1 >
Usage:
If an XOFF has been received from the host, data will not be sent to the host
until the host sends an XON. During the XOFF phase, the host is free to carry
on other chores and accept data from other devices.
Used only with RS-232
.
Definition:
This option enables the host to send the XON and XOFF command as a
single byte transmission command of start (
^Q ) or stop ( ^S ).
Serial Cmd:
< K140,2 >