Balluff BTL7-S5 M J-DEXC-TA12 Serie Manual De Instrucciones página 57

BTL7-S5_ _ (_)-M_ _ _ _-J-DEXC-TA12
Magnetostrictive Linear Position Sensor – Rod Style
6
SSI interface
6.1 Principle
SSI stands for Synchronous Serial Interface and describes
a digital synchronous interface with a differential clock line
and a differential data line.
With the first falling cycle edge, the data word to be output
is buffered in the BTL to ensure data consistency. Data
output takes place with the first rising clock edge, i.e. the
BTL supplies one bit to the data line for each rising clock
edge. In doing so, the line capacities and delays of drivers
t when querying the data bits must be taken into account
v
in the controller.
The max. clock frequency f
Clk
length (see Technical data on page 23, Fig. 8-2). The t
time, also called monoflop time, is started with the last
falling edge and is output as the low level with the last
rising edge. The data line remains at low until the t
has elapsed. Afterwards, the BTL is ready again to receive
the next clock package.
SSIn
T
Clk
Clk
1 2
Data
MSB
T
Clk
Clk
t
v
Data
Clk
Data
T = 1 / f SSI clock period, SSI clock frequency
Clk Clk
T = 1/f Sampling period, sampling rate
A A
n Number of bits to be transmitted (requires n+1 clock impulses)
t = 2 · T Time until the SSI interface is ready again
m Clk
t = 150 ns Transmission delay times (measured with a 1 m cable)
v
www.balluff.com
is dependent on the cable
m
time
m
3 4 5
t
v
T
A
With the BTL7-S5_ _B/F-M..., position data is determined
and output in a timely manner and synchronous to the
external sampling period. For synchronous operation, the
sampling period T must be in the range
A
T ≤ T ≤ 16 ms. The BTL switches to asynchronous
A,min A
operation outside of this range. If the minimum sampling
time is undercut, the BTL outputs the same position value
several times. The external sampling rate is then greater
than the internal rate. In addition, T
so that the next clock package does not occur in the t
range of the previous package.
t
m
n n+1
LSB
Ignition protection "d"
Flameproof enclosure
must be long enough
A
m
english 17