Rockwell Automation T80015 Application Note Trusted SC300E Migration Process - Manual (Page 4)

Trusted TM
AN-T80015
Issue 01 Apr 08 AN-T80015 Page 4 of 16
1.3. Tags, Discretes, Registers
Create tags to get diagnostic data from modules and wire them to the appropriate board in
the Toolset. Create logic programs to derive alarms from diagnostic data, for example
processor temperature, processor voltage etc.
Using the information in the system folder create a spreadsheet of all the tag names,
discretes and registers along with descriptions and any other relevant data. This
spreadsheet can be easily manipulated into a format which can be imported into the Toolset.
The standard SC300E will print alarm and diagnostic data directly to a printer whereas
Trusted
TM can not. You need to use SOE (Sequence of Events) to capture changes of
Boolean variables, so duplicate any tags needing to be monitored with a different name
(prefix with S for example) and wire them to SOE boards in the I/O wiring.
1.4. Application logic
Decide on the language to be used for the main application logic. It may be a good idea to
use ladder logic to mirror the current system so as to minimise the change for the users.
Trusted
TM ladder logic, using the FBD/LD editor, can be made to look very similar to SC300E
ladder logic although not all SC300E functions can be directly replicated.
Some logic uses registers instead of individual discretes, especially where data is gathered
from a whole module or function block, eg GDIA or FALT
The application logic should include the safety ladders as described in SS728 Appendix 1
1.4.1. Execution Speed
Trusted TM operates the SC300E I/O scanning asynchronously from the application scan,
since the I/O scanning is operated by the 8161 Bridge Modules and reported to the processor
as requested. The Trusted
TM application scan was measured at the minimum 32
milliseconds, which is due to the ‘sleep period’ set in the system INI configuration. The
processor is only using about two thirds of the 32ms scan; the rest is free for diagnostics and
background functions.
The faster application scan time in Trusted TM and the asynchronous I/O handling means that
Trusted TM programs must account for the delays expected in the SC300E.
1.4.2. Printed messages, reports and events
SC300E is able to print reports and events, controlled by the application. Trusted TM has no
printer output. However, it has two event logs. The processor holds an event log with 200
entries, which automatically records all system faults and actions without any intervention
from the application. This reports all module faults and swaps as well as program downloads
and Reset pushbutton presses. There is also a Sequence of Events log (SOE) which records
changes to Boolean (digital) variables, complete with timestamps. These timestamps are to
the nearest millisecond but are not absolutely accurate due to the disconnection between the
Trusted
TM application and the real I/O in a hybrid system. Native Trusted TM I/O modules can
record SOE timestamps on arrival to the system.
There is also an analogue event logger called Process Historian if required, but usually
analogues are trended on the DCS or other graphics station.