PLC Programming

Sampling Trace
Dialog Box for Trace Configuration
A Boolean or analogue variable can be entered into the field Trigger Variable. The input assistance
can also be used here. The trigger variable describes the termination condition of the trace.
In Trigger Level you enter the level of an analogue trigger variable at which the trigger event occurs.
When Trigger edge positive is selected the trigger event occurs after an ascending edge of the
Boolean trigger variable or when an analogue variable has passed through the trigger level from
below to above. Negative causes triggering after a descending edge or when an analogue variable
went from above to below. Both causes triggering for both descending and ascending edges or by a
positive or negative pass, whereas none does not initiate a triggering event at all. Trigger Position is
used to set the percentage of the measured value which will be recorded before the trigger event
occurs. If, for example, you enter 25 here then 25 % of the measured values are shown before the
triggering event and 75% afterwards and then the trace is terminated.
The field Sample Rate is used set the time period between two recordings in milliseconds. The
default value "0" means one scanning procedure per cycle.
Select the mode for recalling the recorded values: With Single the Number of the defined samples
are displayed one time. With Continuous the reading of the recording of the defined number of
measured values is initiated anew each time. If, for example, you enter the number '35' the first
display contains the first measured values 1 to 35 and the recording of the next 35 measured values
(36-70) will then be automatically read, etc.. Manual selection is used to read the trace recordings
specifically with 'Extras' 'Read trace'.
6-44 CoDeSys V2.3