Fieldbus

What is fieldbus ?

                 Fieldbus is a digital, two-way, multi-drop communication link among intelligent measurement and control devices. It is a “standardized” digital communication for industrial automation. It is a local area network in field.

                 Computer system used in the industrial sector are connected by a networks generally as fieldbus. Fieldbus systems are way to communicate systems with computers and instruments to a single network in a manufacturing plant and allow for real time control and monitoring.

                 Fieldbus industrial network can be broken down into four levels, each with increasing level complexity as show below...

Network Hierarchy

               
  In above picture only three levels shows because field level can be divide into sensor bus network and device bus network.


Now understand each layer from bottom

• Sensor bus network - It is least complex network developed for industrial applications.

• Device bus network - It is similar to sensor bus network only the difference is that it is connected to so many many instrument and even connected to variable frequency drives and motor control centers. It is some what complex as compared to sensor bus network.

• Control bus network - It is increasingly complex network than device bus network. It is the most advanced networks used on the factory flour and hence data communication happens at a high level. PLC's or Programmable logic controller are connected to each other along with HMI (Human interface machine/station) to allow complete installation or configuration of instruments connected in a network. Smart instruments can be connected to this network level.

• Management/Enterprise bus network - This network level connects all computer and departments together. It is the most complex network level than all other levels. This level of network stored the data or information in systems.

This is some what look like this...

Network architecture

To know other communication protocols click below links...

Foundation fieldbus
Profibus
Modbus
HART

For more information on Industrial networks go through following PDF.

Click here

Comparison of field-buses 

	Foundation Fieldbus (H1)	ControlNet	DeviceNet	Ethernet
Speed	38.4 KBPS	5 MBPS	125 or 250 KBPS	10 or 100 MBPS
Length	1900m	250-1000m	500m	100m
Number of devices	32 devices	40 or less devices	64 devices	1024 nodes