Unit 5 PLC Programming - Amazon Simple Storage Service (S3)
1
Unit 5 PLC Programming The Mitsubishi FXo PLC
5.1) The Loading Bay Door PLC Programme
© Online Skills Training
2 THE LOADING BAY DOOR PLC PROGRAMME
www.onlineskills.training
5.1)
Now that you have :-
Established the merits of Programmable Logic Controllers V discrete wiring. Applied Mitsubishi FXo Element numbering to Ladder Logic circuits. Used the FXo programming panel to enter a simple programme (10 operations.) Used the FXo programming panel to enter the AND Instruction. Used the FXo programming panel to enter the OR Instruction. Tested the programmes for satisfactory operation using simulator switches.
………….you are now equipped to write a simple programme to control
the Loading Bay Door
Don't worry ! there are lots of notes to help along the way.
3 THE LOADING BAY DOOR PLC PROGRAMME
www.onlineskills.training
5.1
The Loading Bay Door PLC Programme
Upper L/sw
Motor
Lower L/sw
The Loading Bay Door to a factory is opened and closed using control buttons and a keyswitch. The door is operated by a motor which can be made to rotate in both directions. Two limit switches mounted on the door frame ensure that the motor is switched off when the door is completely opened or closed.
Open Close
Mounted on the door frame (on the outside of the factory) there is a panel with two buttons and a keyswitch. The keyswitch must be operated in conjunction with either of the buttons to start the motor. The keyswitch is necessary to prevent unauthorised entry to the factory from the outside.
Key/sw Inside the factory there is also a panel but this has just two buttons.
Open Close
4 THE LOADING BAY DOOR PLC PROGRAMME
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5.1 Your task is to…. 1) Draw a Ladder Logic circuit for the Loading Bay Door. 2) Apply Mitsubishi Element numbering to your drawing. 3) Write a programme listing for your drawing. 4) Enter your programme listing into the PLC. 5) Test the operation of your programme using simulator switches. 6) Remove the simulator switches from the PLC and connect the pushbuttons, limit switches and relays and demonstrate the operation of your Loading Bay Door.
Tips This programme will use : The AND circuit The OR circuit Combinational Logic Inputs Outputs Programming instructions not yet covered. (we will attend to these as they
arise).
Also, the motor has two windings :
Energise the first winding and the motor shaft rotates clockwise Energise the second winding and the motor shaft rotates counter-clockwise
5 THE LOADING BAY DOOR PLC PROGRAMME
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5.1 Draw your ladder logic circuit here.
Programme listing
I/O listing and description.
6 THE LOADING BAY DOOR PLC PROGRAMME
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This page is intentionally left blank……..you could use it for drawings etc.
7 THE LOADING BAY DOOR PLC PROGRAMME
www.onlineskills.training
5.1
The Loading Bay Door PLC Programme
(Questions you may be asking) Should I enter the limit switch input either as a normally open or a normally closed element in the programme ?
If it should be a normally closed HOW do I enter it ? Do I need to enter the Keyswitch as two separate contacts ? How do I Load TWO rungs onto the ladder diagram ? Should I consider some form of protection in case of limit switch failure ? How can I protect the electrical circuit in case BOTH motor directions are selected together ?
How do I EDIT my programmes.
READ ON
8 THE LOADING BAY DOOR PLC PROGRAMME
www.onlineskills.training
The Loading Bay Door PLC Programme
5.1
Some Answers to the Questions
Should I enter the L/S input as a N/O or a N/C element in the programme ? The limit switch may be entered either as a N/C or a N/O element, you need to try it out both ways......... but watch out for some safety implications!
If it should be a N/C … how do I enter it ?
Compare these examples:-
a) X1
X2
Y2
X3
X4
Y3
b)
To Enter the N/C element (AND NOT function) it is necessary to use the ANI instruction.
ANI ........... means AND INVERSE
Above circuit would be:-
LD X3 ANI X4 OUT Y3
Try it out………………………….
To energise (or operate) the OUTPUT Y2 we need to close switches X1 AND X2
Note that a N/C has now been entered into the programme and is to be activated by a switch connected to input X4 Remember though that the element has been programmed to be already closed without the need for the switch to be activated. So the circuit logic to energise the output is:Close switch X3 AND NOT switch X4.
However, you might want to leave the plc input for the limit switch entered as a normally open in the programme but actually wire the switch up to its normally closed contact.
9 THE LOADING BAY DOOR PLC PROGRAMME
www.onlineskills.training
Unit 5 PLC Programming The Mitsubishi FXo PLC
5.1) The Loading Bay Door PLC Programme
© Online Skills Training
2 THE LOADING BAY DOOR PLC PROGRAMME
www.onlineskills.training
5.1)
Now that you have :-
Established the merits of Programmable Logic Controllers V discrete wiring. Applied Mitsubishi FXo Element numbering to Ladder Logic circuits. Used the FXo programming panel to enter a simple programme (10 operations.) Used the FXo programming panel to enter the AND Instruction. Used the FXo programming panel to enter the OR Instruction. Tested the programmes for satisfactory operation using simulator switches.
………….you are now equipped to write a simple programme to control
the Loading Bay Door
Don't worry ! there are lots of notes to help along the way.
3 THE LOADING BAY DOOR PLC PROGRAMME
www.onlineskills.training
5.1
The Loading Bay Door PLC Programme
Upper L/sw
Motor
Lower L/sw
The Loading Bay Door to a factory is opened and closed using control buttons and a keyswitch. The door is operated by a motor which can be made to rotate in both directions. Two limit switches mounted on the door frame ensure that the motor is switched off when the door is completely opened or closed.
Open Close
Mounted on the door frame (on the outside of the factory) there is a panel with two buttons and a keyswitch. The keyswitch must be operated in conjunction with either of the buttons to start the motor. The keyswitch is necessary to prevent unauthorised entry to the factory from the outside.
Key/sw Inside the factory there is also a panel but this has just two buttons.
Open Close
4 THE LOADING BAY DOOR PLC PROGRAMME
www.onlineskills.training
5.1 Your task is to…. 1) Draw a Ladder Logic circuit for the Loading Bay Door. 2) Apply Mitsubishi Element numbering to your drawing. 3) Write a programme listing for your drawing. 4) Enter your programme listing into the PLC. 5) Test the operation of your programme using simulator switches. 6) Remove the simulator switches from the PLC and connect the pushbuttons, limit switches and relays and demonstrate the operation of your Loading Bay Door.
Tips This programme will use : The AND circuit The OR circuit Combinational Logic Inputs Outputs Programming instructions not yet covered. (we will attend to these as they
arise).
Also, the motor has two windings :
Energise the first winding and the motor shaft rotates clockwise Energise the second winding and the motor shaft rotates counter-clockwise
5 THE LOADING BAY DOOR PLC PROGRAMME
www.onlineskills.training
5.1 Draw your ladder logic circuit here.
Programme listing
I/O listing and description.
6 THE LOADING BAY DOOR PLC PROGRAMME
www.onlineskills.training
This page is intentionally left blank……..you could use it for drawings etc.
7 THE LOADING BAY DOOR PLC PROGRAMME
www.onlineskills.training
5.1
The Loading Bay Door PLC Programme
(Questions you may be asking) Should I enter the limit switch input either as a normally open or a normally closed element in the programme ?
If it should be a normally closed HOW do I enter it ? Do I need to enter the Keyswitch as two separate contacts ? How do I Load TWO rungs onto the ladder diagram ? Should I consider some form of protection in case of limit switch failure ? How can I protect the electrical circuit in case BOTH motor directions are selected together ?
How do I EDIT my programmes.
READ ON
8 THE LOADING BAY DOOR PLC PROGRAMME
www.onlineskills.training
The Loading Bay Door PLC Programme
5.1
Some Answers to the Questions
Should I enter the L/S input as a N/O or a N/C element in the programme ? The limit switch may be entered either as a N/C or a N/O element, you need to try it out both ways......... but watch out for some safety implications!
If it should be a N/C … how do I enter it ?
Compare these examples:-
a) X1
X2
Y2
X3
X4
Y3
b)
To Enter the N/C element (AND NOT function) it is necessary to use the ANI instruction.
ANI ........... means AND INVERSE
Above circuit would be:-
LD X3 ANI X4 OUT Y3
Try it out………………………….
To energise (or operate) the OUTPUT Y2 we need to close switches X1 AND X2
Note that a N/C has now been entered into the programme and is to be activated by a switch connected to input X4 Remember though that the element has been programmed to be already closed without the need for the switch to be activated. So the circuit logic to energise the output is:Close switch X3 AND NOT switch X4.
However, you might want to leave the plc input for the limit switch entered as a normally open in the programme but actually wire the switch up to its normally closed contact.
9 THE LOADING BAY DOOR PLC PROGRAMME
www.onlineskills.training
