Jetter JetWeb JX2-CNT1, Руководство пользователя

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11.1 Reading in SSI data
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11.1.1 Standard Format
In standard format, the position bits do not include leading or trailing zeroes.
However, special bits or a parity bit may be included directly after the position bits.
Fig. 15: SSI Standard Format
11.1.2 Fir-Tree Format
In the fir-tree format all position resolutions are output always with the same number
of clocks. There is a center line (for example between clock 12 and 13) which divides
the resolution into number of revolutions (to the left of the center line) and steps per
revolution (to the right of the center line). If less than 12 bits are needed for the
number of revolutions, unused places are filled with leading zeroes up to the required
length of 12 bits. On the other hand, if less than 12 bits are needed for the number
of steps per revolution, unused places are filled with trailing zeroes up to the required
length of 12 bits.
Here, special bits or a parity bit can be added, as well. However, only after the zero
bits which have been added to reach the required length, for example, starting from
clock 25.
Fig. 16: SSI - Fir-Tree Format