definition of "bus" in industrial automation

[unsaint32]

I am studying Turck Ethernet gateway BL20, Universal IO bus system. The product brochure describes it as "the I/O is bus-independent."

I know the concept of bus in electrical applications, such as a bus bar where multiple wires tap out from one wire. In automation, does the term "bus" just mean a communication protocol, through which different protocols can communicate to the central PLC?

BTW, in my application, BL20 is connected to CLX5K 1756 L71's ethernet module. In that case, can the ethernet be referred as a bus?

Thanks.

 

[Lancie1]

In that case, can the ethernet be referred as a bus?

Yes, the name calls it a "Universal IO bus system". Universal means that it should work with many types of communicaiton protocols, including Ethernet. Probably it has built-in converters that will send th I/O to several different "buses". Check the specifications to find out just how many different comm protocols they reall mean by "universal". Most likely it is not an infinite number.

 

[unsaint32]

It says "Supports the fieldbus protocols PROFIBUS-DP, Device NetTM, CANopen." Why does it not say Ethernet?


Here is the link location of the document about Turck Bl20 gateway.


http://stevenengineering.com/tech_support/PDFs/46BBL20IO.pdf

 

[Ken Roach]

"Bus" is often used in electronics to refer to some method of transferring data; you've got USB and SATA and the FSB, for example, inside your computer.

In industrial automation, "Bus" and "Fieldbus" often mean the network protocol and media used to connect automation devices together.

Turck BL20 and BL67 are the same products in different physical cases. I'm using some BL67 on EtherNet/IP now.

The manual you have is probably just out of date: BL20 network adapters support several non-Ethernet networks (Profibus DP, CANOpen, DeviceNet) and several Ethernet based networks (EtherNet/IP, EtherCAT, ProfiNet, and Modbus/TCP).

http://www.turck-usa.com/Products/Networks/BL20/

 

[daba]

Ethernet in any shape or form can NOT be given the colloquial moniker "bus" system.

Bus implies physical connection....