Setup guide

OSx Migration Cookbook August 30, 2006
17 – Testing the Migration
Running OSx and
PCS 7 side by side
One of the ways to determine the success of a migration is to run an
original station and a newly migrated station side by side. Ideally
alarms and action requests that are triggered on the original station
will also trigger on the migrated station. How this is set up depends
on what install.tag files were used to create the PCS 7 project.
Install.tag files that originate via Siemens’ Data Extraction
Services, or directly from OSx 4.1.2A contain alarming
information. Install.tag files that originate from Tistar via Siemens’
Data Extraction Services, directly from OSx 4.1.1, OSx 4.1.0x, or
from APT, do not.
When PCS 7/505 DBA reads an install.tag file that has alarming
information in it, it configures those tags and only those tags to be
alarmable. In such a case, the tags designated as alarmable in PCS 7
will match those configured in OSx.
When PCS 7/505 DBA reads an install.tag file without alarming
information in it, it assumes that all tags are to be designated as
alarmable. In that case which tags are designated as alarmable in
PCS 7 differs from OSx. Such a difference can also occur if the
alarmability designation is changed in DBA or new alarm tags are
added that did not exist in OSx.
Once such a difference between PCS 7 and OSx is introduced, the
difference cannot be removed even if the tags that are different are
changed back. This is because OSx and PCS 7 use internal ids to
communicate alarmability to the 505 PLCs. That allows the PLCs
to inform OSx and PCS 7 when an alarm or action request occurs.
This mechanism is called Report by Exception (RBE) and the ids
are called RBE ids. It is these ids that are in the install.tag files.
Before the difference was introduced, the RBE ids in the install.tag
files caused both systems to use the same ids for the same tags.
Once the difference was introduced, new ids were generated which
cannot be changed back to the original since the RBE id is not
accessible from the DBA user interface.
When both PCS 7 and OSx are using the same RBE ids, then both
can run side by side communicating with the same PLCs and both
should see alarms and action requests triggered at about the same
time. When they have different RBE ids, then RBE should be
turned off on the OSx side to avoid showing the wrong alarms or
action requests. OSx 4.1.2A has the ability to turn off RBE built in.
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