ABB S800, Руководство по эксплуатации продукта

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Section 3 Technical Data and Performance Capacity and Performance
3BSE015969-600 A 121
Capacity and Performance
Advant Fieldbus 100 Load
The bus load is calculated with different figures according to the bus length:
• for bus length max 2000 m (2200 yards), use Table 21
• for bus length max 8500 m (9300 yards), use Table 22
• for bus length max 15000 m (16400 yards), use Table 23 .
To calculate the bus load in percent (AF100%load), at the required Cycle Time, the
CI810/CI820 (FCI) loading per station and the I/O Module Type quantity times the
per cent loading.
For bus load calculation, use the formula:
AF100
%load
= CI810/CI820
load
+ S800 I/O Module 1
load
+ S800 I/O Module n
load
+......
Calculation of load for AF100 with a length of max 2,000 m (2,200 yards)
Due to the organization of the Advant Fieldbus 100 scans, some constraints are
imposed on the transmissions. To guarantee message transfer etc., at least 30% of
the fieldbus load is reserved. The remaining load (up to 70%) can be used for S800
I/O station loading and other station loading.
Below is an example for an I/O station with one CI810 FCI, 2 AI810s,
two AO810/AO810V2s, four DI810s and four DO810s using 128ms cycle time for
AI and AO modules and 64ms for DI and DO modules:
AF100
%load
= 0.033% + (2 x 0.197%
AI810
) + (2 x 0.221%
AO810/AO810V2
)

+ (4 x 0.138%
DI810
) + (4 x 0.146%
DO810
) = 2.005% Load
The calculated load of Advant Fieldbus 100 must be equal to or less than 70%.