Siemens SIMATIC MOBY D System Manual page 59

Metal-free area
To guarantee perfect functioning of the individual installation versions, all larger metal parts
in the vicinity of the antennas must be removed.
Figure 4-20
Figure 4-21
Metal in the vicinity of the antennas
If metal in the vicinity of the antennas cannot be avoided, the following must be noted:
● There must be a minimum allround gap of 100 mm between the antenna and metal.
● The influence of the metal depends heavily on its size and shape. Thin metal rods have
● Larger metal surfaces (edge length > 50 mm) in parallel with the antennas or labels result
● Metal parts under the conveyor belt change the direction of the magnetic lines of force.
● The metal parts must not form closed loops or circuits. If necessary, these must be
MOBY D
System Manual, 01/2010, J31069-D0147-A6-7618
Metal-free space _side view (using the example of tunnel arrangement on a conveyor
belt)
Metal-free space _plan view (using the example of tunnel arrangement on a conveyor
belt)
Serious loss of sensing range must be expected above 50 mm. There is no discernible
influence at distances greater than 150 mm from the metal.
less influence on the magnetic field than large surfaces.
in a short-circuit of the magnetic lines of force. As a result, the labels cannot be read.
Serious loss of sensing range must be expected as a result. Horizontally aligned labels
cannot be read in such cases.
electrically interrupted at one point.
Planning the MOBY D system
4.3 Installation guidelines
59