Fieldbus Technology & Output Types
Fieldbus is a name given to a collective group of standardised network protocols used within machine automation and system controls.
These protocols connect Programmable Logic Controllers (PLCs) to the components which do the work of automation, for example, sensors, actuators, lights, switches, valves, contactors and encoders.
The object of a fieldbus system is to enable the PLC to instruct the output device to change its status (i.e. move, return, on/off) and to receive information from the same device or other devices on the same network.
In the early days of PLCs, this was done with many cables (multi-core wiring, cable looms and harnesses), each directly hardwired to a component.
A fieldbus system replaces the mass of cables with typically just two wires so that we can call a fieldbus system a digital, two-way, serial or two-wire system.
Fieldbus systems share a significant advantage over old hardwired systems. Cable elimination, speedier commissioning, and fewer fault opportunities combine to reduce capital expenditure and operational expenses in automation systems.
Automation PLC manufacturers started to develop in-house bus systems, which were limited to their products in the 1980s. The need was for any manufacturer of input/output devices (sensors, actuators) to be able to connect using the same fieldbus protocols.
From this came the open fieldbus systems that we know today. An open fieldbus is available to any manufacturer to build into their product using the desired fieldbus protocol.
Fieldbus protocols and other output types are described in the table below. There are many protocols; however, we have listed the most popular and readily available within our encoder range.
|Absolute encoder basics - SSI
|Absolute encoder basics - BiSS
|Absolute encoder basics - Profibus
|Absolute encoder basics - DeviceNet
|Absolute encoder basics - CANopen
|Absolute encoder basics - Interbus
|Incremental encoder basics - push pull
|Incremental encoder basics - push pull with complementary signals
|Incremental encoder basics - alarm function
|Incremental encoder basics - RS422 with sense
|Incremental encoder basics - RS422 TTL