Page 922 - Sensors and Systems - North American Catalog
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Identification Systems
Introduction
less costly and can be used where very little abuse is expected.We have
the right tag for virtually any application.
Tag/Head Size Choices
It is important to note that if you choose a small tag, you should choose a
small head. There is very little to be gained in a mismatch either way. The
most efficient combinations are those where the head is similar in size to
the tag.
System selection criteria
Cycle time
Typically, the higher the frequency the faster data can be transferred to
and from the RFID tag. Other times must be taken into consideration
to understand the complete system cycle time. You must take into
consideration the following:
• Upper level bus-system scan times of networks like DeviceNet,
PROFIBUS, Ethernet, and RS-232 will change depending on
network loading, baud rate, etc.
• PLC scan time: The PLC may only see the rung that receives the
RFID data every 30 ms. The cycle time of the entire system cannot
be faster than the PLC scan time.
• Data transfer to and from the tag
Data transfer time
Each frequency and each RFID family have different read/write times.
The possible data rates depend on the communication frequency. A 125
kHz system offers typical data rates of 40/130 bytes per second (write/
read) while a high frequency system offers 230 write/3000 read bytes
per second. Additional time must be calculated for the data transfer on
the fieldbus and processing in the PLC. This may be a determining factor
for installation, and will be required if read-on-the-fly speeds need to be
calculated. Typically, the more you want to read the more time it will take.
Maximum passing speed
The passing speed is calculated using the data transfer time between the
tag & head, and the field size. The field size is based on the size of the
read head. The larger the head the more time the tag can stay in the field
and the faster the tag can pass. Being too close or too far away reduces
system performance.
Generally, the following rule applies:
Vmax = Read field width [m]
Read time [s]
For short range systems, if the object passes at about half the maximum
read distance, the diagonal of the read head can be used as the read
field width if the code/data carrier has roughly the same diameter as the
read head.
Typically only 1/2 to 1/3 of the maximum passing speed is recommended
for practical use. This will tallow for retries required due to noise and
interference on the line. Though retries are highly unlikely they are a
necessity on any industrial interface.
Advantages of the IDENT
Control
system
•
The system is completely shielded and can be easily connected with a
ground potential. The read head cables are also shielded to provide the
highest level of EMC safety.
•
Up to four read/write heads can be connected and a mixed mode of
different frequency ranges is possible.
•
Trigger sensors can be connected to start read/write commands.
•
The quick disconnect design means that all components can be
connected easily and swapped over quickly
•
The 24 VDC power supply is obtained through a separate M12 plug; a
red LED indicates reverse polarity, a green LED indicates correct power
connection.
•
The robust metal housing can be mounted to the DIN mounting rail in
the control cabinet using the integrated snap-on hook (IDENT
Control
) or
suitable mounting aids (IDENT
Control
Compact). Three mounting holes
make it suitable for field mounting in IP67 applications.
8.4 RFID Handheld Devices
Product description
Our handheld devices represent a mobile extension of the IDENT
Control
system. RFID handheld devices are available for LF and HF tags. The read
data can be stored in the device and assigned a prefix, suffix, timestamp,
and checksum, enabling the devices to be safely integrated into logistics
and production processes.
LC display and keyboard
The design is similar to that of a cell phone and is intuitive to use. The
handheld device has a keyboard and a multiline display.
Application-specific functions
The JavaScript programming language is used to control the display,
execute all the commands in a routine, and assign soft keys. If you wish to
configure your own interface for the device, please contact Pepperl+Fuchs.
Interfaces
The handheld device has different interfaces through which it can
communicate with a computer.In addition to the wireless Bluetooth interface,
the handheld device also has RS232, PS/2, and USB wired interfaces.You
set the parameters of the individual interfaces directly via the user interface
on the handheld device. Compatible interface accessories are available
from Pepperl+Fuchs.
Power supply
A lithium-ion battery provides power to the handheld device. Batteries and
battery chargers are available from Pepperl+Fuchs.
Identification Sytems RFID
8
Identification Systems RFID,
Control Interfaces
8
.1
Identification Systems RFID,
Heads and Transponders
8
.2
Identification Systems RFID,
Handheld
8
.3
Identification Systems RFID,
Accessories
8
.4
