User's Manual

24
S2510 Reader - Reference Guide April ’00
3.1 Introduction
Where multiple readers are operating in the same area, it is necessary to coordinate
the activities of those readers to avoid mutual interference. This is known as synchro-
nization. Synchronization in this context means that the readers in your application
are controlled in such a way that they do not interfere with each other.
There are several types of synchronization that can be used depending on the situ-
ation in a particular application, for example: the type of transponder, the type of op-
eration performed on that transponder (Charge-only read, General read, Program
page, Lock page), the size of the antennas and the speed of the transponder. The
different kinds of synchronization are described in section 3.2. How to actually set-
up your system to use the synchronization you’ve chosen is described together with
the other installation procedures in Chapter 5.
The distance that readers’ antennas have to be separated before the need for some
method of synchronization is required, varies with local conditions, for in addition to
purely airborne (radiated) interference, signals can travel from one reader to another
via metal structures (conducted). Metal structures can include the frames of metal
buildings, reinforcing bars in concrete floors and power or data cables.
3.2 Types of Synchronization
The S251B Reader can be configured to synchronize in a number of different ways:
No Synchronization (3.2.1)
Wireless Synchronization (3.2.2)
Wired (3.2.3)
Combined Wireless/Wired (3.2.4)
Master/Slave Synchronization (3.2.5)
Carrier Phase Synchronization (3.2.6)
3.2.1 No Synchronization
This option is only used in conjunction with Software synchronization, or if there is
only a single reader. No sync. and Master/Slave sync without acknowledgement are
the fastest methods of reading transponders.
If all readers are connected by the same RS485 data network, coordination of the
readers can be controlled directly by the Host Computer. For example, the Host
Computer may issue a Broadcast command for all readers to simultaneously perform
a read cycle and buffer the result. Another technique possible using the data network
is to issue individual commands to each reader in turn. This technique is used when
writing data to Multipage Transponders (MPTs). Where a PLC has a number of
point-to-point connections to readers, it is also possible to coordinate the activities
via the ladder logic. With Software synchronization all readers will be simultaneously
transmitting or, each reader individually operating. In both cases the readers can be
configured to have No Synchronization.