Allen-Bradley 1747-SN - RIO Scan Time Calculation (TRIO; Example Discrete I;O Throughput Without Block Transfers Present

SpecificationsA–4
Publication 17476.6 - July 1996
RIO Scan T ime Calculation (T
RIO
)
The RIO scan time is calculated by identifying the baud rate and
image size of each logical device on the RIO link. Locate the
corresponding time value in the following table. If you are using
multiple logical devices, add the time values together to determine
the total RIO scan time (T
RIO)
.
T
RIO
= T
adapter 1
+ T
adapter 2
+ T
adapter 3
RIO Scan Times for Adapters
Adapter
Baud Rate
Adapter
Size
57.6K
115.2K 230.4K
1/4 logical
rack
6.0 ms 3.5 ms 2.5 ms
1/2 logical
rack
6.5 ms 4.0 ms 2.75 ms
3/4 logical
rack
7.5 ms 4.5 ms 3.0 ms
Full logical
rack
9.5 ms 5.5 ms 3.5 ms
Example Discrete I/O Throughput without Block Transfers Present
An SLC 5/03 is controlling an RIO link running at 115.2K baud that
has the following adapters:
• One 1747-ASB module module is configured as a 1/2 logical rack
starting at logical rack 0.
I/O chassis slot 1 contains 1746-IB16, 16 point input module
I/O chassis slot 2 contains 1746-OB16, 16 point output module
• Two adapters are each configured as full logical racks (logical
racks 1 and 2).
• Three adapters are each configured as 1/4 logical racks (logical
rack 3).