PLC Programming

3 - We Write a Little Program
For the other TRAFFICSIGNAL colors we need two more networks. To create the first one execute
command 'Insert' 'Network (after)' and insert an EQ-Box like described above. Then select the
output pin of this box and use again command 'Insert' 'Box'. In the new box replace "AND" by "OR".
Now select the first output pin of the OR-box and use command 'Insert' 'Assign' to assign it to
"GELB". Select the second input of the OR-box by a mouse-click on the horizontal line next to the
three question marks, so that it appears marked by a dotted rectangle. Now use 'Insert' 'Box' to add
a further EQ-box like described above. Finally the network should look like shown in the follwoing:
Function block TRAFFICSIGNAL, instruction part
In order to insert an operator in front of another operator, you must select the place where the input to
which you want to attach the operator feeds into the box.
Then use the command 'Insert' 'Box'. Otherwise you can set up these networks in the same way as
the first network.
Now our first POU has been finished. TRAFFICSIGNAL, according to the input of the value STATUS,
controls whichever light color we wish.
Connecting the standard.lib
For the timer in the POU WAIT we need a POU from the standard library. Therefore, open the library
manager with 'Window' 'Library Manager. Choose 'Insert' 'Additional library'. The dialog box appears
for opening files. From the list of the libraries choose standard.lib.
CoDeSys V2.3 3-3