Alien Technology ALR-8780, Инструкция по интерфейсу

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CHAPTER 2
Reader Fundamentals
This chapter provides an overview of the major features found in an Alien RFID
Reader. Specific instructions for setting up a reader are provided in the previous
chapter. Reader commands and their uses are covered in the next chapter.
Introduction
The most basic function of the RFID Reader is to read RFID tags and to give a
user or application access to a list of these tags. The RFID Reader is designed to
perform this function either connected to a host via serial cable, or on a network.
To assist in the administration of networked operation, the reader has two
important features designed to simplify network management:
Reader "heartbeats" allow network applications to easily discover
readers on a network.
Autonomous Mode allows unattended readers to look for tags and send
notification messages to listening services on the network when certain
conditions arise.
These important concepts, along with the basics of communicating with the
reader, are discussed in this chapter.
Reader Discovery and the Reader Heartbeat
One of the problems common to many network appliances is simply discovering
the address of the device on the network. To operate these devices over the
network, users must know the device’s IP address.
If an IP address is hard-coded into the device, this problem is solved, and often a
label on the device can be used to indicate the IP address.
However, many systems do not use hard-coded IP addresses, requiring the
network to assign an address each time the device is booted. This is called
DHCP, which stands for Dynamic Host Configuration Protocol.
DHCP and Automatic Discovery
The DHCP mode of configuration eliminates the need for the user to perform
network configuration for the device. The device simply is plugged into the
network socket, booted, and immediately becomes a citizen of the network,
acquiring its network settings directly from the DHCP server..
However, the user still needs to learn the IP address of the device. All that is
known at this point is that the device does have an IP address and has booted
itself on the network. The actual IP address the device is using is still not known.