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User Manual
GFK-1503F
11.9
SVCREQ 8: Reset Watchdog Timer
Use SVCREQ 8 to reset the watchdog timer during the sweep. Ordinarily, when the
watchdog timer expires, the PLC shuts down without warning. SVCREQ 8 allows the timer
to keep going during a time-consuming task (for example, while waiting for a response from
a communications line)
CAUTION
Be sure that resetting the watchdog timer does not adversely affect the controlled
process.
11.9.1
Parameter Block Format for SVCREQ 8
This function has no associated parameter block.
11.9.2
Example of SVCREQ 8
In this example, power flow through enabling output %Q0027 or input %I1476 or internal
coil %M00010 causes the watchdog timer to be reset.
Figure 187
11.10
SVCREQ 9: Read Sweep Time from Beginning of
Sweep
Use SVCREQ 9 to read the time in milliseconds since the start of the sweep. The data format
is unsigned 16-bit integer.
11.10.1
Output Parameter Block Format for SVCREQ 9
The parameter block is an output parameter block only; it has a length of one word.
address
Example of SVCREQ 9
In the following example, the elapsed time from the start of the sweep is always read into
location %R0200. If it is greater than 100ms, internal coil %M0200 is turned on.
The Service Request Function
time since start of sweep
Chapter 11
Jan 2020
188
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