Rockwell Automation 1747-BSN Backup Scanner Module - Manual (Page 168)

Publication 1747-UM010B-EN-P - September 2003
A-4 Specifications
The formula to calculate the maximum backup scanner discrete I/O
throughput without BTs present is:
T
dm-nbt
= 2T
ps +
2T
RIO +
T
adp +
T
SNo +
T
SNi +
T
id +
T
od
T
dm-nbt
= The maximum discrete throughput without BTs in
milliseconds (ms)
To calculate T
dm-nbt
throughput, substitute values for the variables in
the formula above. Locate these values in the following documents:
Variable Variable Description Location of Variable
T
ps
The total processor scan time (ms) Measured or estimated
T
RIO
The total RIO scan time (ms) See the section RIO Scan Time
Calculation (T
RIO
) on page A-5.
T
adp
The adapter throughput delay. For a
1747-ASB, this is two ASB
backplane scan times. adapter user manual
T
SNo
The backup scanner module output
delay time (ms) See the section Backup Scanner
Output Delay Time (T
SNo
) on page
A-14.
T
SNi
The backup scanner module input
delay time (ms) 5 ms (constant value for all formulas
in this appendix)
T
id
The input module delay time (ms) I/O product data and I/O instruction
sheets
T
od
The output module delay time (ms) I/O product data and I/O instruction
sheets