{"id":63459,"date":"2024-10-16T08:00:00","date_gmt":"2024-10-16T02:30:00","guid":{"rendered":"https:\/\/ye1o34zhk8.onrocket.site\/?p=63459"},"modified":"2024-09-17T12:48:54","modified_gmt":"2024-09-17T07:18:54","slug":"seven-segment-display-programming","status":"publish","type":"post","link":"https:\/\/instrumentationtools.com\/seven-segment-display-programming\/","title":{"rendered":"Seven Segment Display Programming with Structured Text"},"content":{"rendered":"\n

We have seen how a seven segment display<\/strong> plays a very important role in many types of indications that we see in our daily lives. If we need to control its logic through PLC<\/a>, then a new programmer has many options to choose from the language to write it. One of the most highly used and efficient level languages is structured text.<\/p>\n\n\n\n

In this post, we will see how to write a seven segment display logic in a PLC program using structured text language.<\/p>\n\n\n\n

Seven Segment Display<\/h2>\n\n\n
\n
\"seven-segment-display-working-animation\"
Example<\/figcaption><\/figure>\n<\/div>\n\n\n

Let us understand the case scenario first. There are four PLC digital inputs<\/strong> and seven PLC digital outputs<\/strong>. For a number to be displayed, the inputs will come in sequence as per the below truth table.<\/p>\n\n\n\n

In correspondence to the input sequence received, the outputs will turn on accordingly and display the LED segment<\/a> with numbers. Refer to the second image for more understanding, where you can co-relate this table with the display.<\/p>\n\n\n\n

Input I0<\/td>Input I1<\/td>Input I2<\/td>Input I3<\/td>Output O1<\/td>Output O2<\/td>Output O3<\/td>Output O4<\/td>Output O5<\/td>Output O6<\/td>Output O7<\/td>Display<\/td><\/tr>
0<\/td>0<\/td>0<\/td>0<\/td>1<\/td>1<\/td>1<\/td>1<\/td>1<\/td>1<\/td>0<\/td>0<\/td><\/tr>
0<\/td>0<\/td>0<\/td>1<\/td>0<\/td>1<\/td>1<\/td>0<\/td>0<\/td>0<\/td>0<\/td>1<\/td><\/tr>
0<\/td>0<\/td>1<\/td>0<\/td>1<\/td>1<\/td>0<\/td>1<\/td>1<\/td>0<\/td>1<\/td>2<\/td><\/tr>
0<\/td>0<\/td>1<\/td>1<\/td>1<\/td>1<\/td>1<\/td>1<\/td>0<\/td>0<\/td>1<\/td>3<\/td><\/tr>
0<\/td>1<\/td>0<\/td>0<\/td>0<\/td>1<\/td>1<\/td>0<\/td>0<\/td>1<\/td>1<\/td>4<\/td><\/tr>
0<\/td>1<\/td>0<\/td>1<\/td>1<\/td>0<\/td>1<\/td>1<\/td>0<\/td>1<\/td>1<\/td>5<\/td><\/tr>
0<\/td>1<\/td>1<\/td>0<\/td>1<\/td>0<\/td>1<\/td>1<\/td>1<\/td>1<\/td>1<\/td>6<\/td><\/tr>
0<\/td>1<\/td>1<\/td>1<\/td>1<\/td>1<\/td>1<\/td>0<\/td>0<\/td>0<\/td>0<\/td>7<\/td><\/tr>
1<\/td>0<\/td>0<\/td>0<\/td>1<\/td>1<\/td>1<\/td>1<\/td>1<\/td>1<\/td>1<\/td>8<\/td><\/tr>
1<\/td>0<\/td>0<\/td>1<\/td>1<\/td>1<\/td>1<\/td>1<\/td>0<\/td>1<\/td>1<\/td>9<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\"Seven<\/figure>\n\n\n\n

Programming with Structured Text<\/h2>\n\n\n\n

Now, let us write this program. Refer to the below image. In the first four lines, we are moving the values of four inputs in the corresponding bits of a single word. Due to this, we get different values of the word.<\/p>\n\n\n\n

The value of this word is the same as the display number.<\/p>\n\n\n\n

\"Seven<\/figure>\n\n\n\n

Now, after these first four lines, we are using a case statement. A case statement is used to execute different conditions based on the value of the variable referred<\/strong>. In our case, we are referring to the input status variable. So, based on its current value, we write 0 or 1 to the seven outputs<\/a>. Each case value ends with \u201c:\u201d <\/strong>and each statement ends with \u201c;\u201d<\/strong>.<\/p>\n\n\n\n

Basically, we are just moving true or false values in the digital outputs based on the input conditions. Whatever may be the input value, it will write a corresponding value to the word and this word will then be used as a reference for writing the outputs.<\/p>\n\n\n\n

In place of case statements<\/strong>, we can also use if-else statements<\/strong>. But then, the logic would have become a little bulkier and larger to look at. This means, that we would have to write a total of 10 if conditions for the logic. So, we simplified it more by using a case statement.<\/p>\n\n\n\n

This logic looks simple in structured text. Imagine using it in ladder language<\/a>. We would have to write so many rungs with various parallel conditions for turning the output on.<\/p>\n\n\n\n

Task For You:<\/strong> Now program the 7 segment display to show the alphabets as shown in the above animation.<\/p>\n\n\n\n

In this way, we saw how to write a seven-segment display logic in a PLC program using structured text language.<\/p>\n\n\n\n

Read Next:<\/strong><\/p>\n\n\n\n