How to connect LED displays and what is the logics behind LED display connection? What is the structure of LED control system, and how to calculate how many LED cabinets can be loaded by our LED controller?
In this article, we will talk about the fundamental knowledge of LED display control system – some basic but essential points for every LED display screen owner and provider should know. We will discuss the overall structure of LED control system, how to calculate loading capacity, and the LED screen connection logic in a simple manner. Now, let’s get start!
Warm up - How LED Displays Come from?
Before we understand what is LED control system, let’s know the structure of LED screens. As you may know, LED display module is the smallest unit of LED cabinet, meaning the cabinet consists of several modules according to certain rules.
There will be receiving card and HUB card inside the cabinet and connected to the LED display modules through cables. Generally, there should be one receiving card inside the cabinet. However, with the development of high-resolution LED displays, sometimes one receiving card is not enough.
And then , the LED display will be composed by a certain amount of LED display cabinets. Now, have you understood how the LED display screens come from? The logic is simple: LED module, LED cabinet, and finally LED screen! We have the screen now, so how to display images on it? To achieve this, we should build up our LED control system.
What Is LED Panel Connection?
When we come up LED panel connection, we often need to do the work of cable connection, signal connection and LED cabinets, modules or display connection!
Doing this, we need to know the connection logics, how to calculate parameters and operation of corresponding LED control software.
In the following content, we will discuss them steps-by-steps. Of course, all the contents will be easy to understand. Just read the post until to the end to get these information that will definitely help you.
1. What Is LED Display Control System?
1.1 Basic Structure
The basic structure of LED control system will be described below:
The control computer will be connected to the sending controller by USB or Ethernet cables for sending the control command to the LED sending controller.
Moreover, there will be signal cables such as HDMI/DVI/DP to connect the computer and the controller so the video signals can be transmitted.
Then we will connect the LED screen wall with the LED video controller through Ethernet cables by different output ports. Then, we can get the basic structure of common LED display control system!
However, there is other cases which involves a component we often hear about – LED video processor.
1.2 LED Control System with Video Processor for LED Screen
If we assume the source resolution is 1366*768, and the screen resolution is 700*500, meaning the input source resolution is bigger than that of the display. As a result, the screen can only show part of the image.
But if we want to display the entire image, what can we do? In this case, we can introduce the LED video processor to the control system, which will adjust the source resolution to 700*500!
After changing the video source, the entire image can be completely showed on the display as below.
You can basically think the video sources will be transmitted to the video processor for LED screen firstly, and the video processor will play corresponding roles such as zooming or serving other functions to the input sources.
Now the LED display control system structure will be like this:
The functions of LED screen processors can be listed but not limited to:
(1) Images zooming
LED display screens can only show the images whose resolution is compatible with that of the screens. As a result, when the video sources resolution is bigger than screen resolution, the images may only be showed partly.
The video processor for LED screen can make the images be performed completely on the screen regardless of the original image resolution.
(2) Conversion and switching of signals
The video processor supports conversion of different signals, and also allows the quick switching of different input signals.
(3) Improvement of image quality
Because the pixel pitch of LED displays is much larger than some other kinds of displays, therefore, the industry has put forward higher requirements for the image processing technology.
A high-quality LED video processor can modify and improve poor images by performing a series of advanced algorithms, thus bringing viewers better visual effect.
(4) LED screen wall splicing
As LED screen industry has already ushered in high-definition and giant size era, the physical resolutions of LED screen wall sometimes are huge.
LED video processor can deal with the splicing function to drive the LED walls with large resolution in an cost-effective way.
(5) Management of multiple images
LED video processor can deal with multiple same signals or different signals, thus having the capability of multi-images processing.
2. Loading Capacity - How to Calculate?
When we are talking about the loading capacity, we only focus on the pixel level (the total number of pixels).
For one output port, the loading capacity is 650,000 pixels, and for LED screen controller with two output ports, the loading capacity will be 1.3 million pixels. For example, Novastar MTRCL300.
2.1 Cabinet Resolution
So, how to get the cabinet resolution? To calculate this, we should know the cabinet dimension and pixel pitch.
For example, the cabinet dimension is: 1000*1000mm, and the pixel pitch is P3.91.
The pixel resolution = 1000/3.91*1000/3.91 = 256*256
You may have figured out the formulas by yourselves already:
(1) Pixel resolution = Pixel width*Pixel height
(2) Pixel width = Cabinet width/Pixel pitch
(3) Pixel Height = Cabinet height/Pixel pitch
Now we have obtained the cabinet resolution 256*256, so how many such cabinets can be loaded by one output port?
Now let’s do the practise:
2.2 Number of Cabinets Can Be Loaded:
For each output port, the loading capacity is 650,000 pixels:
(4) The number of cabinets = Output put capacity/Cabinet resolution
In this case, the cabinet number = 650,000/(256*256) ≈ 9
So each output port can load 9 cabinets.
2.3 Do We Have Different Loading Capacities of Each Output Port?
You may want to ask: is the loading capacity of each output port of controller is a fixed number as 650,000 pixels? The answer is no. We can figure out different values when we have different conditions.
The capacity = 1 Gbps*Usage rate/Frame rate/(R bit depth+G Bit depth+B bit depth)
The 1 Gbps equals to 109, usage rate is 93.6%, and the default value of frame rate is 60Hz. In this case, we set the color depth of RGB is 8.
So we can calculate the capacity as:
109*93.6%/60Hz/(8+8+8) = 650,000 Pixels
PS: for the definitions of RGB, frame rate and other LED display terms, welcome turn to this article: 30 Frequent LED Display Terms
But if we change the values of color depth and frame rate, you will get different values. In this table, we list some common situations:
| Loading Capacity for each port | Frame rate | Color depth |
| 650,000 | 60Hz | 8bit |
| 325,000 | 60Hz | 10bit/12bit |
| 780,000 | 50Hz | 8bit |
| 390,000 | 50Hz | 10bit/12bit |
Please notice when the color depth is 10bit or 12bit, we will take the value as same as 16bit.
For instance, when the color depth is 10bit, frame rate is 60Hz, we can calculate the capacity as:
109*93.6%/60Hz/(16+16+16) = 325,000 Pixels
Now you have already understood how to get the loading capacity when given frame rate and color depth. Just do a little practice by yourselves, and self-check the answer according to the table!
3. What’s about 4 Outputs Controller?
We all know for one output port, the loading capacity is 650,000 pixels. It is nature to suppose that for LED screen controller with 4 outputs, the value will be 650,000 * 4 = 260,000,0. But is it true? The answer is absolutely no. In fact, it should be 2.3 million pixels. So why can’t we get all the capacity?
Take the most common used input single link DVI, and the largest resolution for single link DVI is 1920*1200 generally (sometimes we will customize the resolution but the maximum value is this), meaning the max resolution is 2,304,000 pixels.
This is why for LED display controller with 4 outputs, the max resolution is 2.3 million pixels. In short, it is because the limitation of input resolution.
4. Max Height and Width Resolution
Here we list the max height resolution and width resolution for different Novastar controller modes. After knowing one of them, you can calculate the another one.
The formula is:
(1) Height = Capacity / Width
(2) Width = Capacity / Height
For instance, for MSD300, the max width is 3840, so the corresponding height should be:
Height = 1.3million / 3840 = 338
The max height is 2560, so the weight should be:
Width = 1.3million / 2560 = 507
| Types of Controller | Total Loading Capacity | Max Width | Max Height |
| MSD300/MCTRL300 | 1.3 million | 3840 | 2560 |
| MSD600/MCTRL600/MCTRL660 | 2.3 million | 3840 | 2560 |
| MCTRL660Pro | 2.3 million | 3840 | 2560 |
| MCTRL R5 | 4.1 million | 3840 | 3840 |
| MCTRL 4K | 8.8 million | 7680
(Need graphics card support first) |
7680
(Need graphics card support first) |
| 4092(Common situation) | 4095
(Common Situation) |
||
| vx4U/Vx4S/Nova Pro HD | 2.3 million | 3840 | 1920 |
| VX6S | 3.9 million | 4096 | 4096 |
| NovaPro UHD Jr | 10.4 million | 16384 | 8192 |
After knowing the concepts of LED control system and loading capacity, we can go on to the next chapter – LED screen connection logic.
5. What Is the Logic of LED Display Connection?
As you can see, he connected eight cabinet with port 1, seven cabinets with port 2, eight cabinets with port 3 and the rest with port 4.
But the system warned him that the network ports exceeded the loading range, meaning the connection is failed. You may want to ask why, because 8*73728 = 589,824 pixels < 650,000 pixels. So, what happened?
Now, we take this chart as the simplified screen connection diagram (10 columns, 3 rows):
The loading capacity of blue area is 192*384*9 = 663,552 pixels > 650,000 pixels. It is obvious the 9 cabinets are too much for one port in this case. And because when the system calculating the loading capacity, it will calculate the values of a complete rectangular area, meaning the loading capacity of 8 cabinets will be considered as the same as that of 9 cabinets！ That is why one port for eight cabinets is not enough.
That means, no matter how many cabinets you connect, seven or eight, the loading capacity will be considered as the same with that of nine cabinets.
Therefore, how can we get the right answer? Just do the LED panel connection like this:
For port one, we connect it with one to eight LED cabinets in the first row; for port two, we connect it with the eight cabinets in the second row; for port three, we use it to load the eight cabinets in the third row, and for the last port, we use it for the 6 cabinets in the right side.
This case tells us the LED screen connection should both take the number of cabinets each port can load and the connection logic into consideration. Please remember the area for one port should be completely rectangular.
Moreover, sometimes the length of cables is one of the determined factors, too. For some companies who equipped cables with specific lengths, even the area is rectangular, and the loading capacity is enough, the connection may not be achieved due to the limitation of lengths of connecting cables.
For instance, some companies will suggest the screens to be connected in some certain ways as much as possible because of the limitation of cables.
Under this circumstances, just ask technicians for the connection methods which both consider the limitation and the other two preconditions.
Next, let us do a little practice to help you understand this knowledge point better in an straightforward way.
Practice:
Question: (1) the resolution of each LED screen cabinet is 128*384 pixels, the screen is 8 columns and 4 rows. (2) We have a Novastar MCTRL600 whose loading capacity is 2.3 million pixels. (3) And the lengths of connecting cables for right to left and top to bottom are 60cm and 80cm separately. How to arrange the display connection?
You get your simplified graphic of this LED display screen like this:
First, we need to calculate the screen resolution:
The screen resolution equals to: 1024*1536 = 157,286,4 pixels
Height: 384*4 = 1536 pixels
Width: 128*8 = 1024 pixels
Second, we will calculate the number of cabinets each port can load:
For each port, the maximum number of cabinets it can load is: 650,000 / 49152 ≈ 13
Please notice there are two preconditions:
(1) The area of calculating the total loading capacity for one port should be rectangular;
(2) Lengths of cables we have.
Finally, we can get the screen connection diagram showed below:
For port 1, we connect it with the eight cabinets in the left side; the port two and port three for the sixteen cabinets in the middle respectively, finally, we use port four for the eight cabinets for the eight cabinets in the right side.
Don’t forget the limitation of cables makes some connection methods can not be achieved. For instance, screen connection like the simplified graphic showed below is not supported:
Now, have you already known the LED display screen connection logic? If you still are a little bit confused, just do the practice one more time, and we believe you can understand this knowledge point well!
