Rockwell Automation 1747-BSN Backup Scanner Module - Manual (Page 169)

Publication 1747-UM010B-EN-P - September 2003
Specifications A-5
RIO Scan Time 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
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 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).
You need to calculate your T
dm-nbt
: the RIO throughput time from
when the input closes on the 1746-IN16 until the output on the
1746-OB16 is on.
Adapter Size
Baud Rate
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