Linking Input Output Cards to PLC Program


Linking Input Output Cards to PLC Program

The PLC program generally contains HW components to achieve some automation tasks. In general, there are different kinds of input-output cards. Input cards receive signals from the devices. The program then decides what to do. It can report or post data to the cloud.

=> We cn scan the HW components by using Visual Studio or inserting I/O cards by observing the electrical drawing. In eaither case, the part of the Visual Studio will be like the following.

The CU2508 real-time Ethernet port multiplier allows the connection of up to eight Ethernet networks. 

The CU2508 is connected to the control IPC via a Gigabit uplink. Eight individually usable 100 Mbit ports are available with full real-time properties. The CU2508 is used in applications in which several Ethernet ports are required that need to be realized externally to the PC. TwinCAT 3 supports the CU2508 with communication via Ethernet (TCP/IP), and EtherCAT.

An EtherCAT coupler is required to connect EtherCAT Terminals with E-bus-communication (series ELxxxx, ESxxxx, EMxxxx) to an EtherCAT network. This coupler relays the communication from the higher-level EtherCAT network to the terminals, or functions as a master itself and generates telegrams. Beckhoff offers different components for different application scenarios. The IO cards can be attached to the coupler or to the PLC itself, depending on the case. We can see in our PLC program list of IO cards as shown in the following image.

We can see all the IO cards if we expand couplers (for example Term 19(EK1501)). Our PLC application can post or store data in the cloud as shown in the following image (note all the images are collected from the internet).


01. If you scan the network and you don’t find the devices (couplers I/O cards etc), consider restarting the PLC, sometimes it helps

See also:

Download the sample from the link given above.

Next, let’s try to understand the PLC data type at

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