ABB S800, Product Manual

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S800 I/O Station Data Scanning Section 3 Technical Data and Performance
142 3BSE015969-600 A
That will give an I/O scan cycle time of 22 ms between the FCI and its I/O modules.
This means that the DIs and DOs will be scanned every 22 ms, the AI810s and the
AO810/AO810V2 every (4*22 ms) 88ms and the AI830/AI830A every (10*22 ms)
220 ms.
For example, a redundant station with CI840, two AI810, one AO810/AO810V2,
two DI810, two DO820 and one AI830/AI830A will give the following I/O scan
cycle time:
2 AI810 => 2*3.00 ms = 6.00 ms

1 AO810/AO810V2 => 1*1.20 ms = 1.20 ms

2 DI810 => 2*0.50 ms = 1.00 ms

2 DO810 => 2*0.50 ms = 1.00 ms

1 AI830/AI830A => 1*0.40 ms = 0.40 ms

1 CI840 => 1*2.10 ms = 2.10 ms
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11.7 ms
11.7 ms is not a multiple of 2, so increase of the value to the nearest multiple of
2 gives 12 ms.
That will give an I/O scan cycle time of 12 ms between the FCI and its I/O
modules. This means that the DIs, DOs, DPs and Standard Drives will be
scanned every 12 ms, the AIs and AOs every (4*12 ms) 48 ms and the
AI830/AI830A, AI835, AI843 and AI893 every (10*12 ms) 120 ms.
Minimum I/O scan cycle time = 4 ms.
Minimum I/O scan cycle time = 4 ms single FCI (CI810) with firmware 1.0 to 1.2

Minimum I/O scan cycle time = 6 ms redundant FCI (CI820) with firmware 1.3
or later.