If you’re venturing into the world of PLC modules, you must first understand how to wire them properly. Just like any electronic device, you need to provide power to activate these modules. Imagine having multiple modules in your PLC setup – you need to power each and every one of them individually for them to function.
To power the PLC input and output modules, you connect the power wires to the front connector. This allows you to easily supply power to the specific module you are working with. When you examine the wires on the front connector, you will come across two types: the wires from different devices in the field and the power wires.
Let’s take a closer look at how the power wires function. For example, in the module we are currently analyzing, the yellow wires are the analog control signals originating from 2-wire pressure transmitters in the field. Additionally, there is a red wire connected to the first terminal of the front connector, which represents the positive 24-volt DC power. Similarly, the blue wire indicates the negative 24-volt power.
Now, you might be wondering where these power wires originate from. Well, they stem from a set of 24-volt DC power supplies that are installed in the same enclosure. This setup ensures a smooth flow of power to the PLC modules.
However, connecting the power wires to the appropriate terminals on the front connector requires some knowledge. It depends on the type of PLC module you are using and the device you intend to connect to it. Each device may have different wiring requirements.
To determine which terminals to connect the power wires to, you need two things. Firstly, you must have the manual for the specific PLC module you are working with. This manual can easily be found on the internet by conducting a quick search using the order number of the module.
For instance, if you have the analog input module with the order number 6ES7 331-7KF02-0AB0, a simple Google search will yield the manual you are seeking. In this manual, you will find detailed information about various S7-300 PLC modules, including the module you are using.
To locate the specific instructions for wiring the module, refer to the table of contents or use the search function (Ctrl+F) to find the relevant page. The manual will provide explicit instructions on how to wire different types of transmitters to the front connector. It will specify the terminals that need to be connected to the positive and negative power wires.
For example, the wiring diagram for a 2-wire transmitter indicates that you should wire the positive to terminal number 2 and the negative to the subsequent terminal. This pattern remains consistent for other 2-wire transmitters as well. On the other hand, if you want to wire a 4-wire transmitter, the manual will offer clear instructions on how to do so. In this case, you will need to connect the positive and negative wires to the front connector, along with an external power source for the transmitter.
Additionally, it is crucial to choose the correct type of front connector for your PLC input and output modules. The type of front connector you use depends on the specific module you have. For S7-300 PLCs, there are generally two types of front connectors available: 20-pin front connectors and 40-pin front connectors.
Ensure that you use the appropriate front connector for each module to maintain a seamless connection. Misusing or mismatching front connectors can lead to malfunctioning or unreliable performance.
By following the guidelines provided in this article, you can successfully wire sensors to a PLC module and ensure the proper supply of power. Remember to consult the specific manual for your module and be cautious when selecting the appropriate front connector for your setup.
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