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Programmer's Guide
t
= t
+ n x t
m
A
s
The minimum size of the object to be detected depends on the velocity as follows:
v
= (l – b) / t
max
m
or
l
= (v
* t
) + b
max
m
Example (with controller ObjectC 100 I/O):
An object with a 50 mm width passes through the monitoring field across the light curtain axis. The light curtain
has a length of 500 mm and a pitch of 25 mm. This means, the light curtain consists of 20 beams. The minimum
measurement calculates to:
t
= 5.3 ms + 20 x 0.275 ms = 10.8 ms
m
v
= (50 mm – 3 mm) / 10.8 ms
max
= 4.3 m/s
4.7.
Blanked beams
The Object100 can be mounted behind a frame, e.g. on a conveyor belt (see Figure 14). Therefore the top and /
or bottom beams may be physically blocked. By defining the first beam offset ("fb_offset") and last beam offset
(lb_offset), the beams in the zones from beam number 1 to "fb_offset" and (n -"lb_offset" + 1) to the last beam will
be ignored, i.e. "fb_offset" = beam 3, (n - "lb_offset" + 1) = beam 12, so objects will only be measured between
and including beams 4 and 11.
Note: "fb_offset" (first beam offset) is the number of blanked beams from the cable end of the light curtain.
"lb_offset" (last beam offset) is the number of blanked beams from the non-cable end of the light curtain
In case where the reverse beam counting direction is being used, the first beam offset and last beam offset
instead refer to beams counting from the noncable end and cable end of the light curtain, respectively.
4.8.
Zone monitoring
Zone monitoring can be used, for example, to sort goods on pallets according to their height. This height sorting
function allows for an efficient use of the storage area, as the pallets can be stored in an area optimally suited to
their height.
© CEDES Safety & Automation AG
t
Minimum measurement time
m
t
Evaluation time = 2.3 ms
A
n
Number of light curtain elements
t
Scan time per beam ≈ 0.13 ms
s
1
see Operation Manual (Part No. 104 906, Chapter 11.2)
v
Maximum velocity of the object
max
l
Length of the object
b
With of the aperture = 3 mm
t
Minimum measurement time
m
Figure 13: An object with length l is detected by optical
beams from the 3 x 8 mm apertures.
http://csa.cedes.com/
1
1
ObjectC 100
27
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