Interrupt Processing S5-95F
12.3.1 Programming OB3
In order to be able to respond quickly to an interrupt, OB3 should be kept as short as possible. Be
sure to optimize the OB3 interrupt processing routine carefully.
Note
• In OB3, direct access is allowed to onboard I/Os only.
• The OB3 runtime may not exceed 8 ms.
The T PY/PW statement transfers the data directly to the relevant onboard outputs, and to the
"normal" PIQ. There is neither an interrupt PII nor an interrupt PIQ.
Note
When flags used in the cyclic program are also used in an interrupt processing routine,
they must be saved before the service routine executes (e.g. in a data block) and
reloaded in the cyclic program.
12-12
EWA 4NEB 812 6210-02
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