Rockwell Automation 1747-BSN Backup Scanner Module - Manual (Page 170)

Publication 1747-UM010B-EN-P - September 2003
A-6 Specifications
1. Use the throughput formula to calculate the maximum
throughput.
T
dm-nbt
= 2T
ps +
2T
RIO +
T
adp +
T
SNo +
T
SNi +
T
id +
T
od
T
ps
= 25.0 ms
T
RIO
= The total RIO scan time (ms)
T
SNo
= See value in the table on page B-13, T
SNo
without M0 File
Writes (Normal Mode).
T
SNi
= 5.0 ms
T
id
= 10.0 ms, which is from I/O module instruction sheets
T
od
= 1.0 ms, which is from I/O module instruction sheets
T
dm-nbt
= 2(25.0)
+
2T
RIO
+ 8.0 + T
SNo
+ 5.0 + 10.0 + 1.0
2. Calculate the total RIO scan time (T
RIO
)
.
Locate the baud rate
(115.2K) and adapter size, which is found in the table on page
B-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
RIO
= T
adapter 1 +
T
adapter 2 +
T
adapter 3
T
RIO
= 1(4.0 ms) + 2(5.5 ms) + 3(3.5 ms)
T
RIO
= 25.5 ms
3. Find T
SNo
on page B-13 in the table T
SNo
without M0 File Writes
(Normal Mode). For this example T
upd
> T
hold
, and there are 4
logical racks configured. Therefore:
T
SNo
= 7.0 ms
4. Substitute all the values for variables in the throughput formula
and solve for throughput:
T
dm-nbt
= 2T
ps +
2T
RIO +
2T
bp +
T
SNo +
T
SNi +
T
id +
T
od
T
dm-nbt
= 2(25.0)+ 2(25.5) + 8.0 + 7.0 + 5.0 + 10.0 + 1.0
T
dm-nbt
= 132.0 ms = maximum throughput