Rockwell Automation 1747-SN Remote I/O Scanner - Manual (Page 102)

Publication 1747-UM013B-EN-P - January 2005
A-6 Specifications
TRIO = 1(4.0 ms) + 2(5.5 ms) + 3(3.5 ms)
TRIO = 25.5 ms
3. Find TSNo on page A-14 in the table TSNo without M0 File
Writes (Normal Mode). For this example Tupd > Thold, and
there are 4 logical racks configured. Therefore:
TSNo = 7.0 ms
4. Substitute all the values for variables in the throughput formula
and solve for throughput:
Tdm-nbt = 2(25.0)+ 2(25.5) + 8.0 + 7.0 + 5.0 + 10.0 + 1.0
Tdm-nbt = 132.0 ms = maximum throughput
Discrete I/O Throughput with Block Transfers (Tdm-bt) Present
The information in this section is used to calculate the discrete
throughput of the 1747-SN Scanner if there are BTs occurring on the
RIO link to any chassis.
If BTs are not present on the RIO link, you must use the Discrete I/O
Throughput without Block Transfers (Tdm-nbt) Present section to
determine your throughput. See page A-3.
The formula to calculate discrete I/O throughput with BTs present is:
T
dm-bt
= The maximum discrete throughput with BTs in
milliseconds (ms)
To calculate Tdm-bt throughput, substitute values for the variables in
the formula above. Locate these values in the following documents:
T
dm nbt –
2T
ps
2T
RIO
2T
bp
T
SNo
T
SNi
T
id
T
od
+ + + + + + =
T
dm bt –
2T
ps
2T
RIO
2T
btx
T
adp
T
SNo bt –
T
SNi
T
id
T + + + + + + + =
od