Online test
Figure 87: Downloader Interface Parameter
In this case the COM port is set to Com2. Change this setting or the 'Bits per
Second' as required. The other settings are usually not changed.
The downloader is a powerful tool which, however, requires more experience
and background knowledge to make full use of its possibilities.
Figure 88: Interrupt Closed Loop by Boot Command
In this context we do not want to describe all possibilities but only give an
important example. It is possible that the controller gets into an uncertain state.
This hardly ever happens in standard operation but e.g. if a fault occurs while
the program is being loaded. The proven measure of resetting, switching off and
switching on again can help. If necessary, the operating system will have to be
loaded again. In any case the connection to the controller can be made. If,
however, a closed loop caused by a fault in the program occurs, this case is
more critical. This can also happen to an experienced programmer, if for
example a forward skip turns into a backward skip when networks are shifted in
the FBD. In this case a reset will not help because the program gets into the
loop again after restart. The relevant function of the downloader will solve this
problem (Figure 88).
Then another reset has to be made, e.g. by switching the operating voltage of
the controller off and on. A few seconds should be waited in between.
Now the usual process of programming should be continued. The downloader is
terminated and we will return to CoDeSys.
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