Using CitectSCADA > Communicating with I/O Devices > The Role of the Protocol

The Role of the Protocol

I/O Devices support at least one protocol – which governs the kind of commands and data you can exchange with the device. They vary significantly in functionality and in complexity. However, because CitectSCADA supplies the protocol drivers, the engineer does not need to know the details of the protocol.

Most modern devices support two or more protocols. This gives engineers flexibility in designing appropriate communications architectures. Sometimes there is a simple protocol that provides basic access to device functionality, and a more comprehensive and complex protocol. Occasionally the protocol is closely linked to the transport layer used – particularly in the case of proprietary protocols and communications hardware.

Which protocol you choose depends on:

In many cases, a specific card or module is necessary in the I/O Device to support additional protocols.

Using Industry Standard Protocols

The automation and associated industries have developed a number of standardized protocols for communicating with I/O Devices. Because these protocols are open and developed collaboratively, they allow a greater degree of connectivity and longevity than other options.

The following list shows some of the prominent communication standards used in the automation industry that are supported by CitectSCADA:

As CitectSCADA allows you to choose whatever protocol you need for the situation, you can choose to use these protocols where supported by your I/O Device.

This is particularly useful when you have a mix of I/O Device brands but you want to simplify and use one common protocol.

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