Rockwell Automation 1747-ASB Remote I/O Adapter - Manual (Page 134)

Publication 1747-UM006B-EN-P - June 2003
A-6 Specifications
1747-ASB Module Backplane Scan Time (T
bp
)
The 1747-ASB module backplane scan time is determined by the type
of I/O modules in the 1747-ASB chassis and the baud rate. To
calculate the 1747-ASB module backplane scan time (T
bp
), first add
the I/O module scan times together to determine the base backplane
scan time (T
b
):
T
b
(T
base backplane scan time
)
(1)
= T
I/O module 1
+ T
I/O module 2
Locate the appropriate I/O module scan times in the following table:
Now substitute the base backplane scan time (T
b
) into the appropriate
equation, based on your baud rate, to solve for the 1747-ASB module
backplane scan time (T
bp
):
(1) Only modules mapped to the 1747-ASB image; unmapped modules are not scanned.
Backplane Scan Times (T
b
)
I/O Module Scan Time (ms)
4-point input 0.210
8-point input 0.210
16-point input 0.325
32 point input 0.560
2 word specialty input 0.625
4 word specialty input 1.100
6 word specialty input 1.575
8 word specialty input 2.048
4-point output 0.170
8-point output 0.170
16-point output 0.273
32-point output 0.470
2-word specialty output 0.620
4-word specialty output 1.028
6-word specialty output 1.440
8-word specialty output 1.745
4-, 6-, and 12-point combination 0.380
Baud Rate 1747-ASB Module Backplane Scan Time (T
bp
)
57.6K baud 1.15T
b
+ 1.38
115.2K baud 1.32T
b
+ 1.58
230.4K baud 1.67T
b
+ 2.00