Rockwell Automation 1747-SN Remote I/O Scanner - Manual (Page 101)

Publication 1747-UM013B-EN-P - January 2005
Specifications A-5
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 Tdm-nbt: the RIO throughput time from
when the input closes on the 1746-IN16 until the output on the
1746-OB16 is on.
1. Use the throughput formula to calculate the maximum
throughput.
Tps = 25.0 ms
TRIO = The total RIO scan time (ms)
TSNo = See value in the table on page A-14, TSNo without M0
File Writes (Normal Mode).
TSNi = 5.0 ms
Tid = 10.0 ms, which is from I/O module instruction sheets
Tod = 1.0 ms, which is from I/O module instruction sheets
Tdm-nbt = 2(25.0) + 2TRIO + 8.0 + TSNo + 5.0 + 10.0 + 1.0
2. Calculate the total RIO scan time (TRIO). Locate the baud rate
(115.2K) and adapter size, which is found in the table on page
A-4. Multiply the RIO scan times listed under the 115.2K heading
by the number of each different type of rack that you have. Add
those numbers together:
T
dm nbt –
2T
ps
2T
RIO
T
ADP
T
SNo
T
SNi
T
id
T
od
+ + + + + + =
T
RIO
T
adapter1
T
adapter2
T
adapter3
+ + =