1. Control Precedence Program
Chapter 1 Interlock Program
Write a program where a high priority section can take precedence over other sections of the program.
CAUTION
Click the ladder program area to enable operation. The title bar will turn blue.
Key operations are not enabled when the title bar and menu items are grayed out.
1 Click [Edit Ladder] button on the remote control.
2 Input the program below.
Place the cursor inside the ladder diagram on the left hand side and begin to input data.
These symbols can be input by pressing the following keys.
3 Let's convert the program you have written into a form the PLC can recognize.
Press the [F4] key.
The background of the program is changed from gray to white.
The program has been converted.
If the program has not been input properly, a conversion error message is displayed.
Control Precedence Program
Chapter 2 Program Transfer to PLC
Let's write the program you have created to the PLC.
An actual PLC is not required because a virtual FX Series PLC is already in your computer.
1 The program can be written to the PLC by selecting "Online" - "Write to PLC" in the ladder program area.
2 When the message 'Write completed. The simulation will start.' is displayed, select [OK].
The PLC starts to operate.
The 'RUN' indicator lamp should be lit in the I/O monitor display area of the PLC.

2. If it is not lit, the PLC is not operating.
Next, let's simulate the program you have created.
Control Precedence Program
Chapter 3 Confirm Interlock Program Operation
Let's turn ON the signal light using your program.
1 When [SW1] (X24) on the operation panel is turned ON, the signal light Red (Y0) is lit.
2 Even when [SW2] (X25) on the operation panel is turned ON, the signal light Green (Y1) is not lit.
In this program, the light Green is not lit when the light Red (Y0) is lit because the contact for Y0 is open.
3 Let's try the reverse operation.
Turn OFF [SW1] (X24) and [SW2] (X25) on the operation panel.
Turn ON [SW2] (X25) first and then [SW1] (X24).
Confirm that the operation of the light Green (Y1) which is set ON 'first' takes precedence.
Did you get it right?
No Yes (Go to the next step.)
Control Precedence Program
Chapter 4 Instruction Precedence Program
Learn the program which gives precedence to the input operated 'last'.
This is how it is written.
1 Click [Edit Ladder] button on the remote control.
2 Select "Project" - "New project".
3 Input the program below.
Place the cursor inside the ladder diagram on the left hand side and begin to input data.
These symbols can be input by pressing the following keys.
Control Precedence Program
Chapter 5 Confirm Instruction Precedence

3. Turn ON the signal lights.
1 When [PB1] (X20) on the operation panel is pressed, the signal light Red (Y0) is lit.
2 When [PB1] (X20) on the operation panel is released, the lamp remains lit.
The output status of the signal light Red (Y0) is held by the latched output program.
3 When [PB2] (X21) on the operation panel is pressed, the light Red (Y0) is extinguished and the light Green (Y1) is
lit.
4 When [PB2] (X21) on the operation panel is released, the lamp remains lit.
The output status of the signal light Green (Y1) is held by the latched output program.
Confirm that the operation of the light Green (Y1) which is set ON 'last' takes precedence.
However, in this program the situation that when both [PB1] (X20) and [PB2] (X21) are pressed is not taken account.
This situation is explained in the following chapters by rising/falling edge detection instruction.
Did you get it right?
No Yes (Go to the next step.)
4 Let's convert the program you have written into a form the PLC can recognize.
Press the [F4] key.
5 The program can be written to the PLC by selecting "Online" - "Write to PLC".

4. Did you get it right?
No Yes (Go to the next step.)