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BML-S2C0-Q _ _ _ -M6 _ _ - _ 0-KA _ _ /KF _ _ /KA _ _-S284
Incremental Magnetic Linear Encoder
6
Interfaces
6.1
Interface signals
The sensor head converts the sine and cosine signals from
the incremental sensors into digital A/B impulses and
transfers them to the controller.
6.1.1
Digital incremental measuring system
The sensor transfers the measurement as a differential
voltage signal (RS422) or as an operational voltage (HTL)
to the controller (depending on the variant).
The edge distance A/B corresponds to the resolution of
the sensor head.
Signal periods 360° el.
A
B
Edge distance
Z
Reference impulse
Q1
Q2
Q3
Fig. 6-1:
Digital output signals for forward movement
The digital A/B impulses are interpolated in the sensor head.
The two digital impulses A and B are electrically phase-
delayed by 90°, the algebraic sign of the phase difference
depends on the direction of movement of the sensor
(Fig. 6-2).
Each edge change of A or B is a counting step for the
cycle counter (up/down counter). With a leading signal A,
the counter reading increases and it decreases with a
leading signal B. The controller knows the precise
increment position at all times, without having to
periodically query the sensor (real-time capability).
The position of the Z signal may be different (Q1 to Q4, see
Fig. 6-1). However, it is always located in the correct
physical position and is always one increment wide.
Note:
For correct function, the A and B signal must be
evaluated depending on the direction.
Signal A
Signal B
Increment
Direction of
Forwards
movement
Counter
reading
Fig. 6-2:
BML output signals with cycle counter
www.balluff.com
Q4
Backwards
Sensor head
PLC
E.g.
IC 26C32
Fig. 6-3:
Circuitry of subsequent electronics (RS422)
A, B, Z,
Nerror
4k7
C
Fig. 6-4:
Circuitry of subsequent electronics (HTL)
BML-S...-Q53...
6.1.2
Circuitry for reference position
Depending on the type, the sensor transfers the following
signals:
–
No reference signal
–
A pole-periodic reference signal (period = 10 mm,
reference signal width = edge distance, Fig. 6-1). If
several reference signals must be transferred, an
external selection switch must be mounted at the
desired reference point signal.
Sensor head
PLC
External selection
switch
Fig. 6-5:
Reference position circuitry
A channel
74C14
5.1 V
Reference signal
for the controller
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