ytdivine:
Please refer to the ladder diagram above.
You will notice two colours; green and black. The two colours shows that the user is on online mode. When offline, the entire diagram turns black.
The diagram looks like a climbing ladder hence the name ladder logic.
There is a special computer design by the PLC manufacturer for programming, this computer is called PG (programmer). The PG (Laptop) is very expensive and may cost above #15m.

When there is a problem on the line( many machines put together) that could not be solved by operators, electricians, mechanics, engineers on duty, the next point of call will be the automation guy. You're expected to login your PG to find out the fault.
The moment you go online, you see the signal flow on the PLC. The signal flows from the left side to the right side. The inputs are positioned on the left while output on the right.
The green color indicate the signal while the black color indicate where the signal flow stopped.
Any confusion or questions at this point

Carry on

ytdivine:
In automation, we can group the system into three major units
a, Field devices (sensing devices)
b. Actuators ( action devices eg motors)
c. Program (written instructions)

The signals from the field devices form the input to the PLC while the output from the PLC acts on the actuators.
The output depends on the written logic programs.
Now let's illustrate with this example.
I entered into a hotel named Park inn in saint Petersburg Russia, the main entrance door immediately opened on it's own without human assistance, it closed the moment I entered inside. I have not experience this in Nigeria, maybe such system might exist, I don't know.
Let's explain the automatic door.
It has two sensors, one at the outside, the second position inside. These two sensors are referred as contacts inside the logic program. The door also has a motor(actuator) that open and close it.
Motor action is dependent on the output signal from the PLC.
Let's call the first sensor input A and the second sensor input B.
The moment you stand in front of the door, the sensor detects your presence and send a 24vdc signal to the PLC, the input A/Contact is activated and the coil( output) is energized, the door opens.
The moment you enter inside, the input B/Contact is activated, thereby resetting the coil(output), the door returns back(closed)
Many confusions, feel free to ask your questions.

Please boss, can this knowledge and principle be applied to something as large as a gate? Thanks

ytdivine:
In automation, we can group the system into three major units
a, Field devices (sensing devices)
b. Actuators ( action devices eg motors)
c. Program (written instructions)

The signals from the field devices form the input to the PLC while the output from the PLC acts on the actuators.
The output depends on the written logic programs.
Now let's illustrate with this example.
I entered into a hotel named Park inn in saint Petersburg Russia, the main entrance door immediately opened on it's own without human assistance, it closed the moment I entered inside. I have not experience this in Nigeria, maybe such system might exist, I don't know.
Let's explain the automatic door.
It has two sensors, one at the outside, the second position inside. These two sensors are referred as contacts inside the logic program. The door also has a motor(actuator) that open and close it.
Motor action is dependent on the output signal from the PLC.
Let's call the first sensor input A and the second sensor input B.
The moment you stand in front of the door, the sensor detects your presence and send a 24vdc signal to the PLC, the input A/Contact is activated and the coil( output) is energized, the door opens.
The moment you enter inside, the input B/Contact is activated, thereby resetting the coil(output), the door returns back(closed)
Many confusions, feel free to ask your questions.

Very clear sir., please carry on

ytdivine:
In automation, we can group the system into three major units
a, Field devices (sensing devices)
b. Actuators ( action devices eg motors)
c. Program (written instructions)

The signals from the field devices form the input to the PLC while the output from the PLC acts on the actuators.
The output depends on the written logic programs.
Now let's illustrate with this example.
I entered into a hotel named Park inn in saint Petersburg Russia, the main entrance door immediately opened on it's own without human assistance, it closed the moment I entered inside. I have not experience this in Nigeria, maybe such system might exist, I don't know.
Let's explain the automatic door.
It has two sensors, one at the outside, the second position inside. These two sensors are referred as contacts inside the logic program. The door also has a motor(actuator) that open and close it.
Motor action is dependent on the output signal from the PLC.
Let's call the first sensor input A and the second sensor input B.
The moment you stand in front of the door, the sensor detects your presence and send a 24vdc signal to the PLC, the input A/Contact is activated and the coil( output) is energized, the door opens.
The moment you enter inside, the input B/Contact is activated, thereby resetting the coil(output), the door returns back(closed)
Many confusions, feel free to ask your questions.

Well understood.

Please can you explain how the system will work if there many people going in, say they are on the line or que going into the hotel, how would the outside and the inside sensor respond since at every time someone will be outside and another one inside, because they are on a line/que, just thinking! Thanks

Bright12660:

Please boss, can this knowledge and principle be applied to something as large as a gate? Thanks

Why not, once you have a good logic behind it, it can be translated to reality.

nnewsnjobs:

Well understood.

Please can you explain how the system will work if there many people going in, say they are on the line or que going into the hotel, how would the outside and the inside sensor respond since at every time someone will be outside and another one inside, because they are on a line/que, just thinking! Thanks

Good question.
This is where logic comes in. The example above is to illustrate the concept of sensors and contacts. In actual design, many things come into play like emergency conditions, time to lock the gate, detecting suspicious object/weapons from individuals, crowd of people trooping in etc.
We are not talking about design at the moment, our attention is only to explain types of contacts and what actually represent contacts in the real life. As we advance in this training, we are going to task our brains on different possibilities (Logic)

More inputs before we advance

ytdivine:


Good question.
This is where logic comes in. The example above is to illustrate the concept of sensors and contacts. In actual design, many things come into play like emergency conditions, time to lock the gate, detecting suspicious object/weapons from individuals, crowd of people trooping in etc.
We are not talking about design at the moment, our attention is only to explain types of contacts and what actually represent contacts in the real life. As we advance in this training, we are going to task our brains on different possibilities (Logic)

Thanks for your explanation.
Please can you forward your email to me, I want to share automation design job with you to know if you can handle it. Do me mail at monjerk12@gmail.com

Good morning everyone,

For those showing interest, it's not enough to say you are interested without any other action. You have to check-in at least once a day by dropping a comment on the thread. Doing this will encourage our mentor and also make the class move at a faster pace.
I know we have busy schedules, but we can make it work if we try.

Thank you.

Hello Everyone

Southboy:
Hello Everyone

Hi.. let’s go

Hello guys.. No word from our trainer in a while now, anyone in contact with him ?

Enough people didn't show interest

Southboy:
Enough people didn't show interest

If he can make it affordable for those interested.

Also, we can have a timeframe for it

Rawsh55:


If he can make it affordable for those interested.

Also, we can have a timeframe for it

He has said he is not interested in getting paid, I just think the best way would be to do it outside of nairaland or we have a fixed time for the class.

Southboy:
He has said he is not interested in getting paid, I just think the best way would be to do it outside of nairaland or we have a fixed time for the class.

I support this point

Southboy:
He has said he is not interested in getting paid, I just think the best way would be to do it outside of nairaland or we have a fixed time for the class.

Oh yes., a forum that can be controlled and only interested person would be added..

@ Lecturer sir, please consider our request for the sake of those that are interested.

Southboy:
@ Lecturer sir, please consider our request for the sake of those that are interested.

Am always a busy person. My schedule is always tight. The truth is that you can't learn the course without active participation. It's only a reasonable active persons that can draw my time and energy to this training.
If the training is constrained to limited individuals, the aim is defeated.

Meanwhile, write a ladder logic program that involves two NO and two NC inputs with only a coil as output.
Let see how serious you guys are. Send your work to aniobinnaeee@yahoo.com

Very good input from Rasheed Sanni. May I know your Nairaland user name.

You must learn to develop and task your brain. This is a must for prospective Automation experts. This is a mentorship class.

Only one person responded to my assignment. Where are others?

ytdivine:
Very good input from Rasheed Sanni. May I know your Nairaland user name.

You must learn to develop and task your brain. This is a must for prospective Automation experts. This is a mentorship class.

Only one person responded to my assignment. Where are others?

I’m here.. it’s @Rawsh55

ytdivine:


Meanwhile, write a ladder logic program that involves two NO and two NC inputs with only a coil as output.
Let see how serious you guys are. Send your work to aniobinnaeee@yahoo.com

Guys Let’s endeavor to reply to this 👆

I am interested

I’m interested please

All those interested in the training should indicate by doing the assignment. You must not get it right, what matters most is making an attempt.
That's only way of learning here. Reading alone without active participation cannot take you anywhere.

@Mentor

What’s the way forward.. we can’t afford to stop here

Rawsh55:
@Mentor

What’s the way forward.. we can’t afford to stop here

If we have 5 to 10 active students, then we progress.

Good input from Uzoma Awaka. May I know your nairaland username

Uzoma maybe a guest on Nairaland, if so, please try to register to make things easier for us. He has some advance tools which others can learn from

I would like @Rawsh55 , my runaway class rep @Southboy, and other serious students to upgrade to this level.
The picture below is an input from Uzoma Awaka.
You can have millions of correct answers to my assignment above, that's why it's logic

ytdivine:
I would like @Rawsh55 , my runaway class rep @Southboy, and other serious students to upgrade to this level.
The picture below is an input from Uzoma Awaka.
You can have millions of correct answers to my assignment above, that's why it's logic

Noted

Good attempt from KAY. Remaining two more input to continue.
KAY, what's your nairaland user name?