1747-6.22, Backup Scanner User Manual

Calculating
Throughput
Specifications A-187
The 1747-BSN Backup Scanner’s throughput is determined by using
the formulas provided in this section.
Discrete I/O Throughput without Block Transfers (T dm-nbt) Present
The information in this section is used to calculate the discrete
throughput of the 1747-BSN Backup Scanner if there are no BTs
occurring on the RIO link to any chassis.
If BTs are present on the RIO link you must use the Discrete I/O
Throughput with Block Transfers (T dm-bt ) Present section to
determine your throughput.
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
Tps The total processor scan time
(ms)
APS reference manual
T RIO
T adp
T SNo
T SNi
T id
T od
The total RIO scan time (ms)
The adapter throughput delay.
For a 1747-ASB, this is two ASB
backplane scan times.
The backup scanner module
output delay time (ms)
The backup scanner module
input delay time (ms)
The input module delay time
(ms)
The output module delay time
(ms)
see the section RIO Scan Time
Calculation (T RIO) on page B-4
adapter user manual
see the section Backup Scanner
Output Delay Time (T SNo ) on
page B-11
5 ms (constant value for all
formulas in this appendix)
I/O product data and I/O
instruction sheets
I/O product data and I/O
instruction sheets
Publication 1747-6.22