Basic configuration
Leuze electronic
BPS 307i
51
8
Basic configuration
The parameters of the SSI interface as well as the switching inputs/outputs can be configured via the
webConfig tool (see chapter 9) or via connection hood MS 307 or MK 307.
Devices with connection hood KB 307 can only be configured via the webConfig tool.
8.1
Configuring the SSI interface
8.1.1 Principal functionality of the SSI interface
Data communication of the SSI interface is based on differential transmission as is used for RS 422 inter
-
faces. The position value is transmitted in sync with a cycle (CLOCK) specified by the control, starting with
the most significant bit (MSB); see figure 8.1.
• In the idle state, both the clock line as well as the data line are at HIGH level.
On the first HIGH-LOW edge (1), the data of the internal register are stored.
This ensures that the data are not changed during serial transfer of the value.
• With the subsequent change of the clock signal from LOW to HIGH level (2), transfer of the position
value begins with the most significant bit (MSB).
• With each subsequent change of the clock signal from LOW to HIGH level, the next least-signifi
-
cant bit is transmitted on the data line.
• After the least significant bit (LSB) has been output, the clock signal switches from LOW to HIGH
for one last time and the data line switches to LOW level (end of transmission).
• A monoflop retriggered by the clock signal determines how long before the SSI interface can be
called for the next transmission. This yields the minimum pause time between two successive clock
cycles (t
m
)
If time t
m
has elapsed, the data line is reset to bias level (HIGH) (3). This signals the fully completed
data exchange and renewed transmission-ready state.
• t
m
= 20 µs with master clock frequency 80 kHz - 800 kHz
• t
m
= 30 µs with master clock frequency 50 kHz - 79 kHz
• The update rate (50 µs to 2 ms) of the measurement values at the SSI interface can be configured
via the webConfig tool. Factory setting: 2 ms.
The update rate describes how quickly the data are replaced on the SSI interface by current data.
The measurement value is updated independent of the clock frequency.
