Not very choosy
Fieldbus Interface can be installed on any process control system

A new version Fieldbus Interface Module (FIM) is a good solution for users who plan to expand or retrofit their systems. The module is designed for systems without fieldbus I/O. It allows installation of a large number of field devices using Foundation Fieldbus on any process control system.

The goal of every user is to increase process efficiency, but this often cannot be done without investing time and money. In a BP ethyl acetate production facility at Hull in England, the addition of a catalyst to a subprocess was identified as a critical element. Temperature distribution while the catalyst is being added is an important factor, so high resolution measurement (i.e. a large number of data acquisition points) is necessary. The engineers determined that more than 200 measurement points are needed to provide meaningful process temperature gradients.

Once this information is available, projects like this are usually at a critical juncture, because a large amount of instrumentation is required to achieve the
desired effect in the process. Cable installation requirements alone could kill the project. Laying 250 meters of multi-core cable to the control station at the Hull f
acility would have required erection of a supporting frame and adherence to a schedule which was simply not acceptable. A lucky coincidence and two products where are tailor-made for this type of problem solved the conflict. The Rosemount 848T has eight inputs for resistance thermometers or thermal elements, 13 of which can be attached to a single fieldbus segment using the 3420 fieldbus interface module. Using Foundation Fieldbus (FF), 104 temperature sensors can be polled using a single cable link. By pure accident, the necessary pairs of wire were available for use in an existing cable bundle. Every Foundation Fieldbus segment is now connected via an “old” pair of cables to the control room, and a barrier provides protection in the potentially explosive zone. Nearly 280 temperature sensors on four reactors are polled using three fieldbus segments and two interface modules to provide redundancy. Every fieldbus interface module captures temperature data from the transmitters and uses a Modus link to send the data to the main control system (in this case a TDC 3000). This simplifies data communications to the control system, and it eliminates the need for additional I/Os.
Suitable for any process control system
The Project Manager at BP, Frank Wilson, sees the open design of the interface module, which will work with any process control system, as a major advantage. “We have three Foundation Fieldbus segments in a system which uses conventional control architecture. The line has a Honeywell TDC 3000 control system, and we have added a lot of sensors which can easily be connected using a single Modbus link. We can now exploit the full range of benefits offered by Foundation Fieldbus polling and communications. We are able to poll every sensor which is connected to the Rosemount 3420 interface module using our existing Ethernet link.” The 3420 interface module is based on web server technology, and it simplifies commissioning, configuration and maintenance. The module’s scalable architecture can accommodate up to four FF segments, and it includes power conditioners for supplying power to the fieldbus. Control functions can be moved to the field devices to increase accuracy and productivity. A similar type of project is now underway. There are already plans to use fieldbus segments and two additional 3420 fieldbus interface modules to poll temperature sensors on a vinyl acetate line