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User Manual
GFK-1503F
11.20
SVCREQ 26/30: Interrogate I/O
Use SVCREQs 26 and 30 to check whether the installed modules match the software
configuration. If not, these SVCREQs place appropriate addition, loss, and mismatch faults
in the PLC and/or I/O fault tables. SVCREQs 26 and 30 both perform the same function.
The more configuration faults there are, the longer it takes these SVCREQs longer to
execute.
These SVCREQs have no parameter block. They always output power flow.
11.20.1
Example of SVCREQ 26
In the example, when input %I0251 is ON, the SVCREQ checks the installed modules and
compares them to the software configuration. Output %Q0001 is turned on after the
SVCREQ is complete.
Figure 198
11.21
SVCREQ 29: Read Elapsed Power Down Time
Use SVCREQ 29 to read the amount of time elapsed between the last power-down and the
most recent powerup. If the watchdog timer expired before power-down, the PLC is not able
to calculate the power down elapsed time, so the time is set to 0.
The SVCREQ output is always ON.
11.21.1
Output Parameter Block for SVCREQ 29
This function has an output parameter block only. The parameter block has a length of 3
words.
address
address + 1
address + 2
The first two words are the power-down elapsed time in seconds. The last word is always 0.
The Service Request Function
Power-Down Elapsed Seconds (low order)
Power-Down Elapsed Seconds (high order)
zero
Chapter 11
Jan 2020
199
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