Although fieldbus is an important option for the industry in our opinion it's not a good fit with the new breed of soft PLC's. Using fieldbus with a soft PLC requires a PC card for the fieldbus hardware that is native to the PLC system. We feel that the need for the card often offsets many of the cost gains derived from the fieldbus system. What's needed is a standard hardware platform with the performance of the fieldbus system and the might of the computer industry to bring its cost down. Here again, we say the answer is Ethernet.
Ethernet is the most widely accepted local area network in the industry.
Ethernet is a true industry standard, governed by the IEEE 802.3 specifications relating to hardware design and communication protocol. This open standard ensures that no matter which vendor's equipment is used, inter-operability is guaranteed. 10M bits per second carried over a twisted pair cable terminated on each end with RJ-45 telephone style jacks. The other more increasingly encountered medium is 10Base-F or, 10M bits per second carried over a fiber optic cable for increased noise immunity. Ethernet is also vendor neutral and, therefore, inexpensive to implement.