Balluff BML-S Series, User Manual, Page: 42 / 130

16
7
System selection
7.1 Maximum movement speed, resolution, and
edge distance
There is a connection between the selected resolution of
the sensor head, the minimum edge distance, and the
possible movement speed that is illustrated in Tab. 7-1 and
Tab. 7-2.
BML-S_B/S_E…: system accuracy up to 50 µm
Min. edge
distance
1)
V
max
acc. to edge distance and resolution
Resolution
F G H K
5 µm 10 µm 25 µm 50 µm
D 0.12 µs 20 m/s 20 m/s 20 m/s 20 m/s
E 0.29 µs 10 m/s 20 m/s 20 m/s 20 m/s
F 0.48 µs 5 m/s 10 m/s 20 m/s 20 m/s
G
1 µs 3.25 m/s 6.5 m/s 14.75 m/s 14.75 m/s
H 2 µs 1.5 m/s 3 m/s 7.7 m/s 7.7 m/s
K 4 µs 0.75 m/s 1.5 m/s 3.95 m/s 3.95 m/s
L 8 µs 0.375 m/s 0.75 m/s 1.7 m/s 1.7 m/s
N 16 µs 0.195 m/s 0.395 m/s 0.95 m/s 0.95 m/s
P 24 µs 0.13 m/s 0.26 m/s 0.65 m/s 0.65 m/s
1) Connection between edge distance and counting frequency, see
appendix for table.
Tab. 7-1: BML-S_B/S_E…: Selection aid for maximum movement
speed
BML-S1C…: system accuracy up to 100 µm
Min. edge
distance
1)
V
max
acc. to edge distance and resolution
Resolution
L M N P R
100 µm 200 µm 500 µm 1000 µm 2000 µm
M 10 µs 8 m/s 10 m/s 10 m/s 10 m/s 10 m/s
R 100 µs 0.9 m/s 1.8 m/s 4.2 m/s 8.8 m/s 10 m/s
1) Connection between edge distance and counting frequency, see
appendix for table.
Tab. 7-2: BML-S1C…: Selection aid for maximum movement speed
If using the reference sensor, the max.
movement speed is limited to 10 m/s.
The following applies for 4x evaluation (each edge is
counted):
Counting frequency
of the controller
≥
1
Min. edge distance
Period length =
Counting frequency
4
Example: edge distance = 1 µs
Counting frequency = 1 MHz
Period length = 250 kHz
Important!
– The controller/display must be able to count
the minimum timed edge distances indicated
in the tables (note the counting frequency of
the controller!).
– The min. edge distance can even occur at a
standstill due to the internal interpolation
process.
– Always select the next-higher movement
speed or the next-faster min. edge distance,
otherwise position detection errors may be
created by the controller during evaluation.
Sensor head design for controlling with 4x
evaluation:
Example 1: required resolution: F = 5 µm
► In Tab. 7-1: select column 1.
Max. movement speed = 7 m/s
►
Row 2 = select 10 m/s.
⇒
Edge distance E = 0.29 µs.
Example 2: required resolution G = 10 µm
► In Tab. 7-1: select column 2.
Max. counting frequency of the controller = 0.5 MHz
Edge distance H = 2 µs
► Select row 5.
⇒ Maximum possible movement speed: 3 m/s
Example 3: max. movement speed = 2 m/s
Controller detects min. edge distance M = 10 µs
►
In Tab. 7-2: select row 1.
►
Select column 1.
⇒ Max. possible resolution L = 100 µm (BML-S1C)
Coding in the type code breakdown
BML-S2E0-Q61 _ -M410- _ 0-KA05 (example)
Min. edge distance
Resolution
For further information, see Type code
breakdown on page 22 und 23.
BML-S _ B/C/E0-Q _ _ _ -M4 _ _ - _ 0-KA _ _ /KA _ _-S284
Incremental Magnetic Linear Encoder
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