Rockwell Automation T8110B/T8110 Trusted TMR Processor - Manual (Page 32)

Trusted
TM
TMR Processor T8110B/T8110
Issue 18 Feb 08 PD-T8110B/T8110 32
4.8.3. Application Execution
The Application Execution time has a minimal effect on the total scan time. It is based on the
processing load of the application. While actual application load varies greatly based on numerous
factors, an estimation can generally be calculated based on the number of I/O modules in a system.
The Application Execution time is calculated by multiplying the total number of I/O modules by a
constant time factor.
No. I/O Modules Application Execution Total
( ) x 0.3 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 0.05 ms
4.8.4. Communications
Communications is less easy to calculate, because it can be sporadic and depends heavily on the
details of the configuration. The estimate used in section 4.7 may be used as a rough guide, based on
the I/O module count in the way it affects data volume.
No. I/O Modules No. Comms
Modules Communications Total
( ) x 1.5 ms x (
)
A small improvement in I/O scanning time may be possible if unused slots are disabled in the system
configuration. This will have most effect on systems with many chassis but few modules, e.g. where
each chassis is sited at an outstation with one input and one output module. If a slot is disabled on a
release 3.5 system, the processor ignores it altogether. Note that one unused slot should be left in
service for diagnostic interrogation of suspect modules.