SMAR FI302, Operation, Maintenance & Instruction Manual

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Introduction
III
Introduction
The FI302 is of the first generation of Fieldbus devices. It is a converter mainly intended for interface
of a Fieldbus system to control valve or other actuators. The FI302 produces a 4-20 mA output
proportional to input received over the Fieldbus network. The digital technology used in the FI302
enables an easy interface between the field and the control room and several interesting features
that reduce considerably the installation, operation and maintenance costs.
The FI302 is part of Smar's complete 302 line of Fieldbus devices.
Fieldbus is not only a replacement for 4-20 mA or intelligent / smart transmitter protocols, it contains
much more. Fieldbus is a complete system enabling distribution of the control function to equipment
in the field.
Some of the advantages of bi-directional digital communications are known from existing smart
transmitter protocols: Higher accuracy, multi-variable access, remote configuration and diagnostics,
and multi-dropping of several devices on a single pair of wires.
Those protocols were not intended to transfer control data, but maintenance information. Therefore
they were slow and not efficient enough to be used.
The main requirements for Fieldbus were to overcome these problems. Closed loop control with
performance like a 4-20 mA system requires higher speed. Since higher speed means higher power
consumption, this clashes with the need for intrinsic safety.
Therefore a moderately high communication speed was selected, and the system was designed to
have a minimum of communication overhead. Using scheduling the system controls variable
sampling, algorithm execution and communication so as to optimize the usage of the network, not
loosing time. Thus, high closed loop performance is achieved.
Using Fieldbus technology, with its capability to interconnect several devices, very large control
schemes can be constructed. In order too be user friendly the function block concept was introduced
(users of SMAR CD600 should be familiar with this, since it was implemented several years ago).
The user may now easily build and overview complex control strategies. Another advantage is
added flexibility; the control strategy may be edited without having to rewire or change any
hardware.
The FI302 , like the rest of the 302 family, has several Function Blocks built in, like PID controller,
Input Selector and Splitter/Output Selector, eliminating the need for separate control device. This
feature reduces communication and by that less dead-time and tighter control, not to mention the
reduction in cost.
Other function blocks are also available. They allow flexibility in control strategy implementation.
The need for implementation of Fieldbus in small as well as large systems was considered when
developing the entire 302 line of Fieldbus devices. They have the common features of being able to
act as a master on the network and be configured locally using a magnetic tool, eliminating the need
for a configurator or console in many basic applications.
Get the best result of the FI302 by carefully reading these instructions.