Issue 1.3 17
ibaPDA- Interface- MySQL Conguraon and engineering ibaPDA
■ With output modules, the queue size is 1000 by default:
Producon data, for example, can be wrien via SQL commands. It is important here that
these are also buered and made up for in case of a connecon breakdown.
Commandmeout
By seng the command meout, you determine the maximum me for a statement to be exe-
cuted. If the query or command is not completed before the command meout has elapsed, the
execuon is aborted. The default sengs of query and command dier:
■ SQL query: 5 s
■ SQL command: 30 s
4.3.3 Buer
In output direcon the interface uses a memory buer and addionally a le buer that can be
enabled oponally.
Data to be sent to the target system always passes through the internal ibaPDA memory buer.
If the connecon to the target system exists, the data is sent there immediately. If the connec-
on is lost, or the data cannot be sent out fast enough, the data is temporarily stored in the
memory buer. The memory buer is located in the RAM of the ibaPDA computer and is there-
fore limited and volale. If, for example, the acquision is restarted, the buered data will be
lost. If the memory buer grows beyond the congured size during ongoing acquision, the old-
est values are deleted and thus lost.
To improve this, a le buer can addionally be enabled, which can buer much larger amounts
of data. The data is stored in les in a directory on a local drive of the ibaPDA computer. When
the le buer is enabled, data is transferred from the overowing memory buer to the le buf-
fer. If the acquision is stopped or restarted (e.g. by applying a modied I/O conguraon), data
that may be in the memory buer at this me is also transferred to the le buer.
Aer reconnecng to the target system, the oldest data is always sent rst. Newer values are
added to the buer in the meanme. If there is sll buered data in the le buer when the
acquision is started, it will be handled and processed in the same way.
In terms of SQL statements this means that the statements are buered according to the con-
guraon which was valid at the me of buering. If you change the SQL statement during an
ongoing buering (change and apply in the I/O Manager), the system will sll execute the old
statements as generated at the me of buering aer the connecon has been reestablished.
You congure the buering on the Buer tab in the Outputs secon of the SQL interface.