Table of Contents
Advertisement
V740
RFID Reader Query
Protocol
Reference Guide
This chapter lays the groundwork for the
communication protocol between client software
running on a remote computer and V740 RFID
Readers. The client software can be any kind of
database system, enterprise software, or user
software.
In this chapter, we discuss the underlying transport
protocol used and present the initial
communication protocol RQL. This protocol is
loosely based on the SQL language with
extensions for a better notion of time. This protocol
was designed for rapid prototyping of applications,
where a full query to the Reader can be
encapsulated in a single line of ASCII text. A
simple polling mechanism exists for automatically
receiving tag events and for testing, a connection
can be mode from a standard telnet client.
Transport Protocol
In the current implementation, TCP/IP is used as
the transport protocol. TCP is a connection-
oriented protocol that provides a reliable, in-order
data transport layer with end-to-end checksums
and flow control.
TCP Connection Setup and
Teardown
A session between client software and the Reader
consists of connection setup, data transactions,
and connection teardown.
At present, all connections are initiated only by the
client software. If, for example, the Reader is
configured to automatically forward events and/or
data to the client software but the client software
has not established a connection, then no attempt
V740 RFID READER ANTENNA
OPERATION MANUAL
NOTE. SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE.
14 of 27
is made by the Reader to contact the client
software to establish a connection. Furthermore, if
an extant connection terminates unexpectedly, the
Reader will not attempt to contact the client
software to re-establish a connection. All
responsibility for opening, maintaining, and closing
the connection during a session rests with client
software.
The client software sets up a TCP socket
connection on Reader port 8080. After connecting
successfully, communication between the client
software and the Reader can proceed as described
below. Once the client software has determined
that communication has concluded, the connection
must be terminated at the TCP level. In order to
prevent synchronization issues, each Reader will
support only one TCP connection.
Other transport protocols may be used to
communicate between the client software and its
subjugate Readers. The application-level protocol
discussed below is neutral with respect to the
transport layer.
Event/Query Protocol
The client software can acquire data from the
Readers in two modes: (a) by requesting specific
data or (b) automatically receive events in another
mode. The two modes are discussed in further
detail in the following subsections.
In order to keep the protocol light but
comprehensive, we specify a small set of
commands that allow the client software to fully
configure the Readers and exploit their capabilities.
This minimal set of commands includes the ability
to request reads based on several relevant criteria
(for example, group reads, range reads, reads by
prefix, and so on). The ability to reset the Reader
database and other control capabilities are also
provided for.
Figure 1 Control flow of RQL
REV. 1.1
© OMRON CORPORATION 2004
Advertisement
Table of Contents
