Rockwell Automation 1747-ASB Remote I/O Adapter - Manual (Page 136)

Publication 1747-UM006B-EN-P - June 2003
A-8 Specifications
These values are listed in the Backplane Scan Time table on page A-6.
4. Add the backplane scan times together for each module in slots
one, two, and three.
T
base backplane scan time
(T
b
) = T
I/O module 1
+ T
I/O module 2
+
T
I/O module 3
T
b
= 0.325ms + 0.273ms + 0.625ms + 0.620ms
T
b
= 1.843ms
5. Use the appropriate Total Backplane Scan Time formula found
on page A-6 to calculate the total backplane scan time.
T
bp
= 1.32T
b
+ 1.58
T
bp
= 1.32(1.843ms) + 1.58
T
bp
= 4.01ms
6. 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
A-5. 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(4.0ms) + 2(5.0ms) + 3(3.5ms)
T
RIO
= 24.5ms
7. 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
+ 10ms
(1)
T
dm-nbt
= 2(25)+ 2(24.5) + 2(4.01) + 0 + 0 + 10.0 + 1.0 + 10
T
dm-nbt
= 128.02 ms = maximum throughput
(1) The value of 10 ms is for PLC-5/11, -5/20, -5/30, -5/40, and -5/60 processors only. For all other PLC-5
processors the value is not required.