This tutorial will follow up the tutorial First Steps in Industrial Automation [1] where was explained what is and how to use the Grafcet LVL 1 tool to plan an automatic system for your process. Now you will learn how to evolve from Grafcet LVL 1 to Grafcet LVL 2 and LVL 3.
Parts Required
The software used was drawio because it is a good software to develop this type of schematics and it can be used online (avoiding installations), but you can use any other software like Excel or even a paper and a pencil.
Grafcet LVL 2
There is a big difference between grafcet LVL 1 and LVL 2. On LVL 1 actions and receptions are written without any criteria in the automation area but in the logic of summarizing the process. In another way, on LVL 2 the words are short and objective because it is better to create the logic to automation. Below you can see some examples of the evolve from LVL 1 to LVL 2.
To execute Grafcet LVL 2 first step is to enumerate all your hardware and to exemplify that we will use our use case of the first tutorial. Try to use abbreviations like shown in the below table and in case of having more than one motor, button, sensor, use sequential enumerations to those (M1, M2, B1, B2, S1, S2, etc).
| Grafcet LVL 1 | Grafcet LVL 2 |
| Rotative Motor | M1 |
| Sinalizador vermelho | LED1 |
| Timmer of 20 seconds | T1=20s |
| Increment the counter | C1++ |
In automation systems, you can have actions like turn ON motor but you should need to turn OFF this same motor. In Grafcet LVL 2, as is the same motor, has the same abbreviate (M1). To distinguish this different action, when you need to turn ON have to use M1 and when you need to turn OFF you have to use M1 with a dash over.
Application Example LVL 2
Grafcet LVL 3
This Grafcet LVL 3 is the last tool used before start programming on PLC (Programmable Logic Controller). For that, the main purpose of this is to link the inputs and outputs to the address of PLC used. One more time, you should use sequential numerations. For inputs signals like buttons and sensors you should use the prefix “I” and for outputs signals like motors and LEDs you should use the prefix “Q”.
To execute Grafcet LVL 3 first step is to link your enumerated hardware to your PLC addresses. Below you can see some examples of the evolve from LVL 2 to LVL 3.
| Grafcet LVL 2 | Grafcet LVL 3 |
| M1 | Q0.0 |
| LED1 | Q0.1 |
| S1 | I0.0 |
| B1 | I0.1 |
Application Example LVL 3
The second post on this topic (Industrial Automation) ends here. Do not lose the next post of first steps in Industrial Automation where you will learn which are more used variables types and their properties.
If you have some doubts or want to know more about this Industrial Automation area don’t forget to leave a comment.
