ETAS ES1337.2, Руководство пользователя

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Hardware Features 17
2.1.5 Type “VDA”
“VDA” sensors are also active sensors and, like the “DF11i” sensors, are based
on the Hall effect.
The following figure shows the output signal of this sensor.
Fig. 2-5 Speed Pulse and Data Bits
The speed pulse is output at every “edge” of the encoder wheel – the current
I
H
of this pulse is four times the low level I
L
= 7 mA.
An initial bit that sets the current level to I
L
precedes this pulse. A further nine
bits follow the speed pulse with a current level of I
H
= 2 I
L
.
I
L
= 7 mA
I
M
= 2 I
L
I
H
= 4 I
L
0 2 3 1 4 5 6 7 8
Data Protocol Bits
Speed Pulse
Initial Bit
N S