Omron CX-PROGRAMMER V9 - Page 103

PART 1: CX-Programmer
CHAPTER 2 – Quick Start Guide OMRON
CX-Programmer _Page 20
Writing a Program
The following program sequences a set of traffic lights. The sequence is a standard British
sequence of the following order:
• Red light only;
• Red and Amber lights together;
• Green light only;
• Amber light only.
Writing a ladder program consists of:
• Creating symbols;
• Creating the ladder program;
• Compiling (automatically checking) the program;
• Transferring the program to and from a PLC;
• Comparing the program with the PLC program;
• Monitoring the program during execution;
• Performing an on-line edit (if necessary).
Creating Symbols
An important step in creating a Ladder Program is the definition of those PLC data areas that are to be
referenced by the program. It is possible to skip this step, and use addresses directly within the program. It is
better, however, to create symbolic names for the addresses so that the programs become more readable and
maintainable.
Use the following procedure to create symbols.
1, 2, 3…
1. Click in the Diagram Window and select the View Local Symbols button from the
toolbar.
2. Select the New Symbol button from the toolbar. The Insert Symbol dialog is displayed.
3. Enter ‘AmberLight’ in the Name field.
4. Set the Address or value field to ’10.01’.
5. Leave the Data type field set to ‘BOOL’ to indicate a bit (binary) value.
6. Type ‘Prepare to go / stop’ in the Comment field.
7. Select the OK pushbutton to proceed.
Repeat this procedure for each of the other entries in the following table:
Name Address Data Type Comment
RedLight 10.00 BOOL Stop.
GreenLight 10.02 BOOL Go.
RedLightTimer 1 NUMBER Timer for the red light period.
AmberLightTimer 2 NUMBER Timer for the amber light period.
GreenLightTimer 3 NUMBER Timer for the green light period.
AmberOnlyTimer 4 NUMBER Timer for the amber only period.
RedTimerDone T0001 BOOL
AmberTimerDone T0002 BOOL
GreenTimerDone T0003 BOOL
AmberOnlyTimerDone T0004 BOOL
TimeInterval 48 NUMBER Speed at which the sequence works (ticks).
Note: It is important to use the standard form of addresses in CX-Programmer. Depending upon
their defined type, addresses may have two components – a channel and a bit number. In the