Synchronous And Asynchronous Operation - Balluff BTL7-S5xx-Mxxxx-A/B-SA211-S32/S147/KAxx/FA serie Betriebsanleitung

BTL7-S5 _ _ (B)-M _ _ _ _ -A/B(8)-SA211/SA311-S32/S147/KA _ _ /FA _ _
Micropulse Transducer - 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 transducer. 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
D
equal to the internal sampling period. The transducer
always works with the maximum possible internal sampling
frequency. Due to the measuring principle, the maximum
sampling frequency f is dependent on the nominal
A,max
length of the transducer.
Clk
Data
External
sampling point
Internal sampling
point + processing
New value available
Position delay
16 english
must be kept as short
D
Two boundary conditions must be taken into account
during synchronous operation:
– The external sampling frequency f
62.5 Hz < f < f . The maximum permissible sampling
A A,max
frequency f is shown in Fig. 8-1 on page 20.
A,max
– 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 range
A