Function And Characteristics; Characteristics; Function; Ssi Interface - Balluff Micropulse BTL5-S1 Serie Manual De Instrucciones

BTL5-S1_ _-M_ _ _ _A/B/Z-S32/S147/KA_ _
Micropulse Linear Transducer - Rod Style
2

Function and Characteristics

2.1

Characteristics

Micropulse transducers feature:
– High data security: Output data
are checked for validity and plau-
sibility in the µC.
Very high resolution, repeatability
–
and linearity
– Measurement range monitoring
with "Out of Range" Bit 2
– Immunity to shock, vibration,
and contamination
– An absolute output signal
Wear- and maintenance-free
–
BTL to processor cable lengths
–
up to 400 m
– Pressure rated to 600 bar
– IP 67 per IEC 60529
2.2

Function

The transducer contains a tubular
waveguide enclosed by an outer
stainless steel rod. A magnet at-
tached to the moving member of
the machine or to the cylinder pis-
ton is moved over the rod and its
position constantly updated.
1 2
+Clk
t
t
v
+Data
Fig. 2-1: Pulse diagram, example with 24 bit coding
➀ only for resolution > 5 µm
Position of magnet:
1) out of the measurement range
2) within the measurement range
3) magnet not present
21
"Out of Range" Bit 2 will be set
after the occurence of the event.
Value of the output data 2 0 ... 2
1a) 0
1b) max. at end point + 10 mm
2) proportional to distance
3) 0
Technical data are valid within the
measurement range only, i.e. between
null and end point.
The magnet defines the measured
position on the waveguide. An inter-
nally generated INIT pulse interacts
with the magnetic field of the mag-
net to generate a magnetostrictive
torsional wave in the waveguide
which propagates at ultrasonic
speed.
The torsional wave arriving at the
end of the waveguide is absorbed in
21
.
the damping zone. The wave arriv-
ing at the beginning of the wave-
guide creates an electrical signal in
the coil surrounding the waveguide.
The corresponding value is output
as synchronous serial data (SSI) via
the RS 485/422 interface. This
takes place with high precision
and repeatability within the mea-
suring range indicated as the
nominal stroke length.
At the rod end is a damping zone,
within which no reliable signal is
available, but which may be entered
by the magnet.
The electrical connection between
the transducer, the processor/con-
troller and the power supply is via a
Clock sequence
3 4 23
MSB
➀
Out of
Range
20 : Bit 2
~10 mm
0
Bit 2 ... 2
Fig. 2-2: Output data shown with "Out of Range" situation
cable, which depending on the
version is either fixed or con-
nected using a female connector.
Dimensions for installing the
Micropulse transducer: ➥ ➥ ➥ ➥ ➥ Fig. 3-1
Dimensions for installing the mag-
net: ➥ ➥ ➥ ➥ ➥ Fig. 3-4
2.3
The SSI interface uses 24 or 25
bits depending on the BTL model,
and the position values are sent in
Gray or binary code. The clock
frequency f is a function of the
cable length ➥ ➥ ➥ ➥ ➥ Table 2-1. For the
purposes of error detection bit 2
is provided as an "Out of Range"
message, see Fig. 2-1 and
Fig. 2-2. Sending of the position
values is finished within time t
is started with the falling edge of
the last clock pulse. After this time
the BTL is ready for the next data
transmission.
24
t < t
t
t
t
m
LSB
Null point
1a 2
21
20

SSI interface

m
= 150 ns measured with 1 m cable
v
= 31 µs independent of the clock
m
frequency
3
End point
2 1b
~10 mm
english
21
. It
m
3