Rockwell Automation T8110B/T8110 Trusted TMR Processor - Manual (Page 29)

Trusted
TM
TMR Processor T8110B/T8110
Issue 18 Feb 08 PD-T8110B/T8110 29
4.7.4. Application Execution
The Application Execution time is based on the estimated size of the application. While actual
application size varies greatly based on numerous factors, an estimation of the application size can
generally be calculated based on the number of I/O points in a system. The Application Execution time
is calculated by adding a constant overhead factor to the total number of I/O modules, then multiplying
by a constant time factor
No. I/O Modules Application Execution Total
( + 5 ) x 1.5 ms
If the size of the application is known, or if it can be derived from the application size of a similar
system, the Application Execution time can be calculated directly by multiplying the application size by
a constant time factor.
Size of the Application (in KB) Application Execution Total
x 0.3 ms
4.7.5. Composite Scan Time
The composite scan time is the sum of the Central Module time, Input Module time, Output Module
time, and the Application Execution time.
Central Module Total
Input Module Total
Output Module Total
Application Execution Total
Composite Scan Time
1 The default configuration is for all outputs to be updated each scan, irrespective of a change of state
(or value). If the Trusted TM system is configured to update outputs only when they change, the Output
Module time calculation is as follows: [ (Scan Factor + 4.5 ms) x No. Output Modules ] + [ (Scan Factor
+ 3.1) x DeltaOM ], where “DeltaOM” represents the average number of Output Modules with at least
one channel that will change state (or value) with each composite scan time and is at least 1 for any
system that contains at least 1 Output Module.