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3-7
Section
Mutual Interference Prevention Function
30
3-7
Mutual Interference Prevention Function
If two or more Antennas are used close to one another, they will not operate
properly due to mutual interference. It is possible to reduce the mutual interfer-
ence between the Antennas and use them closer together if the Controllers are
connected together with SYNC cables. Refer to 9-3 Mutual Interference be-
tween Antennas for more details.
The mutual interference distance between Antennas can be reduced by con-
necting the Controllers’ SYNC terminals together to synchronize operation as
shown in the following diagram. One of the Controllers connected in series is set
as the Master and the others are set as Slaves. Be sure to enable the terminators
of the Controllers at the ends of the line and disable the terminators of other Con-
trollers. A maximum of 32 Controllers (the Master and up to 31 Slaves) can be
connected within a total cable distance of 300 m maximum. The Master/Slave
settings can be made using the Controller’s DIP switch or a command sent from
the host device.
Total distance 300 m max.
Master
Slave 1
Slave 2
Slave 31
Switch settings
Master
Termination
resistance set to ON
Switch settings
Slave
Termination
resistance set to
OFF
Switch settings
Slave
Termination
resistance set to
OFF
Switch settings
Slave
Termination
resistance set to ON
Antenna
Mutual
interference
ID Tag
1 m min.
There are two types of synchronous operation: R/W (read/write) synchronous
and RO (read-only) synchronous functions. With R/W synchronization, all com-
mands can be used. With RO synchronization, the commands that write data to
the ID Tags (WT, AD, SB, PW, MK, and WP) cannot be used. The advantage of
RO synchronization is that it requires a shorter communications time than the
R/W synchronization. Refer to 8-3 Communications Time for details.
Item
Synchronous function
RW
RO
No synchronous
function
Synchronous cable
To be connected
Not required
Mutual interference
distance between
Antennas
Short
Long
WRITE command
Possible to use
Not possible to use
Possible to use
Communications
time
Long
Slightly long
Short
Note
1. Be sure to enable the SYNC termination resistance only on the two Control-
lers at each end of the SYNC cable and disable the SYNC termination resist-
ance on all of the other Controllers. The RFID System’s operation will be un-
stable if the terminators are not set correctly.
2. Set the same synchronization setting (RW, RO, or no synchronization) on all
of the Controllers that are connected together with the SYNC cable. If the
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