Siemens CP 243-2 - Manual (Page 138)

AS-Interface Protocol Implementation
A-4
SIMATIC NET CP 243-2 AS-i Master
C79000-G8976-C142/02
How the AS-Interface cycle time depends on the number of connected slaves
The following formula is used to calculate the AS-Interface cycle time depending
on the number of activated slaves.
T
cycl
= (1 + number of activated slaves) * 156
µ
s
If a pair of slaves using the extended addressing mode (A/B slaves) occupies an
address, this pair is counted as a single slave in the formula. Pairs of A and B
slaves are addressed in every second AS-Interface cycle; in other words, the
calculated cycle time is doubled for these slaves.
The calculated cycle time applies assuming that no frames are repeated, there are
no management calls and all slaves are synchronized.
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