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Blocks and Their Functions
9.1.1
Scan Time Trigger (OB31)
By means of a scan time monitor (hardware watchdog) you monitor the time sequence of cyclic
program processing. If program processing takes longer than the cycle monitoring time of 680 ms
set via the hardware, then the S5-95F goes to STOP. This can occur, for example:
•
if the control program is too long
•
if you have programmed an infinite loop.
By calling the integral organization block OB31, you can retrigger the scan time monitor at any point
in the control program, i.e. re-initiate the cycle monitoring time. OB31 is already programmed and
you then only need to call it up. However, you cannot change this organization block.
Calling OB31:
At any point in the control program: Enter JU OB31.
Note
For safety reasons, the scan time is monitored not only by the hardware watchdog but
also by a software watchdog. You specify the monitoring time for the software watchdog
in DB 1; retriggering of this monitoring time in the control program is not possible.
9.1.2
Procedure after Battery Failure (OB34)
The S5-95F checks the status of the battery. In the case of a battery failure, the S5-95F reacts as
follows:
•
The battery failure is signalled
•
A message is entered in the system event DB (see Table 15.2)
•
After the battery failure you must replace the battery within 72 hours. During this time, the
S5-95F calls up OB34 prior to each cycle.
•
If the battery is not replaced within 72 hours, the S5-95F goes to STOP. Prior to this it enters
the error occurred (battery failure) in the system event data block DB254 and calls up the error
handling organization block OB37 once.
9.1.3
Error Handling (OB37)
In the organization block OB37 you can react to signalled errors and messages specifically. OB37 is
called and processed by the operating system every time the S5-95F enters an error or a message
in the system event DB (DB254). Every entry in the system event DB results in OB37 being called
once (no cyclic calling of OB37).
9-2
S5-95F
EWA 4NEB 812 6210-02
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