Synchronous And Asynchronous Operation - Balluff BTL7-S5 M J-DEXC-TA12 Serie Manual De Instrucciones

BTL7-S5_ _ (_)-M_ _ _ _-J-DEXC-TA12
Magnetostrictive Linear Position Sensor – Rod Style
6
SSI interface (continued)
6.4

Synchronous and asynchronous operation

Synchronous operation
A uniform and brief timing is often required for control
applications. The position delay t
and constant as possible Synchronous operation is thus
.
intended for closed control loops. Here, the internal
sensing cycle adjusts itself to the external sampling cycle.
The following graphic clarifies this relationship:
Clk
Data
External sampling
point
Internal sampling
point + processing
New value available
Position delay
Asynchronous operation
During asynchronous operation, the external sampling
frequency is independent of the internal sampling
frequency of the BTL. Depending on the external query
point, the position is more or less current and the position
delay t is not constant. In the worst case, it is equal to the
D
internal sampling period. The BTL always works with the
maximum possible internal sampling frequency. Due to the
measuring principle, the maximum sampling frequency
f is dependent on the nominal length of the BTL.
A,max
Clk
Data
External
sampling point
Internal sampling
point + processing
New value available
Position delay
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must be kept as short
D
Ignition protection "d"
Flameproof enclosure
Two boundary conditions must be taken into account
during synchronous operation:
– The external sampling frequency f
range 62.5 Hz < f < f . The maximum permissible
A A,max
sampling frequency f is shown in Fig. 8-1 on
A,max
page 23.
– The sampling frequency must be kept as constant as
possible.
The sampling frequency is the reciprocal value
of the time between two clock packages and
may not be confused with the SSI clock
frequency.
The following graphic shows the behavior of internal and
external sampling in asynchronous operation:
must be in the
A
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