Foundation Fieldbus (FF) features
- Reduce field wiring costs.
- Intrinsic safety wiring option available to further reduce costs in hazardous environments.
- Same bus used for analog and discrete devices.
- Control (LAS) for the segment may reside in the field devices freeing up space in central controllers.
- Time stamping of control parameters performed in field devices and coupled to control data to optimize operating performance.
- Provides greater controllability and process information.
- Standardized function blocks, representing control and I/O; speed set up.
- Long bus length of 1900m (6,175 ft) and spurs up to 120m (390 ft) span most process systems.
- Supported by over 80% of the world’s process instrumentation suppliers.
Foundation Fieldbus economic analysis
When using a StoneL VCT module and integrating it into the Foundation Fieldbus (FF) network illustrated, there are significant savings. This system consists of 16 automated valve systems located in a cluster approximately 200 feet from the I/O rack. Each of the automated valves is located 20 feet apart in the cluster. Following is an estimated comparison:
Foundation Fieldbus analog point addition to StoneL I/O modules
The StoneL Foundation Fieldbus I/O modules have an auxiliary 4 to 20mA input and a 4 to 20mA output which is powered from the supplemental 24VDC supply bus. Additional savings may result from connecting the 4 to 20mA device directly to the StoneL I/O instead of running wires back to I/O at the controller. The additional analog input would be represented as an AI (Analog Input) function block as part of the StoneL device description.
The 4 to 20mA instrument may be conveniently wired directly into the StoneL I/O module. With a conventional system the control would need a 200 foot run back to the controller. Other savings would result from:
- Reduction in design time because of simpler conduit and cabling systems.
- Reduction in conduit and cabinetry space.
- Right first-time wiring and easier trouble-shooting.
- Faster commissioning.