WRS – Installation Manual
4.10.9 Using the radio frequency channels
4.10.9.1 2.4 GHz ISM band
The WRS system uses the internationally reserved 2.4 GHz ISM (Industrial-Scientific-Medical) band, which
occupies the following frequency range:
• 2400MHz - 2483MHz (worldwide)
The WRS system emitted power is approximately +4 dBm (~2.5mW), which means that it is classified as a class 2
transmission device. There are currently numerous wireless systems that use this frequency range (2.4 GHz), so
it is very important to ensure there is sufficient space available in the frequency spectrum for the WRS to function
reliably.
1. WRS system channels and sub-channels
The WRS system features 79 frequency channels, each one occupying a bandwidth of 1 MHz; to convert the
channel number into the effective frequency value, use the following formula:
Effective frequency = 2402 MHz + Channel number x 1MHz
Each physical channel is divided into 4 logic channels (sub-channels). These sub-channels are identified by
the letters A to D and correspond to the various probe selections that the machine is capable of activating
(see para. 4.11). Selecting the most suitable working channel for each radio system is very important for
guaranteeing constant and reliable communications over time. When compared to other systems, such as
FHSS (Frequency Hopping Spread Spectrum), WRS offers the following advantages:
• It enables users to plan and allocate the way the frequency spectrum is used, by selecting and
defining the channels;
• It allows the system to adapt to any changes in how the frequency spectrum is used by using ACS
(Automatic Channel Selection, see para. 4.10.11).
In order to allocate all 316 available channels (79 frequency channels x 4 sub-channels) correctly, the user
must take into account the isolation capacity of the transceiver in use; our recommendations are as follows:
• Use one channel (frequency) for each machine;
• Use the same channel (frequency) for the transmitters mounted on the same machine, allocating a
different sub-channel to each one;
• Select non-adjacent channels (frequencies) on machines that are installed close together or in the
case of multiple WRI receivers.
In situations where there are multiple systems installed in the same area (factory), it is possible to re-use
channels and sub-channels provided the correct distance is maintained. REF _Ref406054956 \h Table
4-8lists the values that must be respected.
A. Machine with single WRI receiver installed
The most frequently used application consists of a machine equipped with a spindle and one WRI receiver
installed. In this configuration, it is possible to use a different frequency channel for each system installed on
the machine, while the sub-channels will only be used for multiple WRP transmitters.
B. Multiple WRI receivers installed on a single machine
In the case of machines equipped with dual spindles, in order to measure two parts simultaneously it is
necessary to install a WRI receiver for each spindle. In this configuration it is important to ensure that:
• The minimum distance between the devices is respected;
• The WRI receivers are positioned as far apart as possible;
• Identical or adjacent frequency channels are avoided.
C. Installation with two or more machines positioned close together
Given the unpredictable way in which electromagnetic waves are propagated, the machines must never be
treated as though they are isolated systems; in other words, whenever a radio frequency system is installed,
it will influence, and be influenced by, all the other machines that are installed around it. Due to the wide
communication range of the WRS system, when two machines are installed within a few metres of each
other, the two units should be treated as a single, large machine equipped with multiple spindles when
planning the WRS installation layout. Therefore, the suggestions listed in the previous paragraph should be
taken into consideration. This is especially true if the WRI receivers are installed outside the working zone
(as in Figure 4-13), since the WRP transmitter signal may be more attenuated than those emitted by the
surrounding WRS systems.
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