Archived: Functionality of the FP-3000 Network Module

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This document explains the features and benefits of the FP-3000 Network Module.

Contents

Overview

The FP-3000 is an intelligent network interface and controller module that manages a bank of up to nine FieldPoint I/O modules and terminal bases. The FP-3000 network module and the terminal bases snap together to form a high-speed data bus for communications between the FP-3000 network module and any I/O modules in the bank. The FP-3000 includes an H1 Fieldbus interface for direct connection to an H1 FOUNDATION Fieldbus segment. A Fieldbus segment is a multidrop network and can consist of up to 32 H1-compliant devices. You can connect a Fieldbus segment to up to 32 FP-3000 network modules.

The FP-3000 implements FOUNDATION Fieldbus-compliant I/O function blocks, such as Analog Input (AI), Analog Output (AO), Discrete Input (DI), and Discrete Output (DO). These blocks provide functionality such as scaling, trending, and alarming. For example, when you connect a 4–20 mA pressure transmitter to a FieldPoint I/O, you can configure an FP-3000 Analog Input function block to convert from 4–20 mA to engineering units. You can set up alarm limits so that the FP-3000 sends an alarm when the pressure exceeds the limits. The FP-3000 network module can also collect trend samples and broadcast them to applications on a PC.

Connecting Conventional Devices


The FP-3000 network module provides a Fieldbus interface to conventional analog and discrete I/O devices. For example, the FP-3000 makes a 4–20 mA pressure transmitter connected to a FieldPoint 8-channel analog input module behave like a Fieldbus pressure transmitter. By using an FP-3000 network module, you can significantly reduce wiring and installation costs. Instead of running a pair of wires from each 4–20 mA device to your controller, you can mount an FP-3000 network module in the field and run a single pair of wires (called the trunk) from your PC to the FP-3000. You connect the 4–20 mA devices to the FieldPoint I/O modules by short stretches of wire.

Conventional devices connected to I/O modules are made visible as Fieldbus function blocks. Function blocks are software modules which describe the fundamental elements of an I/O or control system. The FP-3000, like any FOUNDATION Fieldbus-compliant device, has one or more function blocks. The function blocks in different devices can be connected to form a distributed control system.

PID Control


The FP-3000 implements the FOUNDATION Fieldbus-compliant PID control function block. This PID can be used to control either an analog output element connected to FieldPoint I/O or a native Fieldbus device, such as a valve, connected to the Fieldbus network. The FP-3000 executes the PID and other function blocks deterministically in accordance to a configured schedule.

Programmable Control


The FP-3000 v 2.3.5 and later implements a function block called the Expression Block which executes a user-defined program. The Expression block has a number of analog and discrete inputs and outputs which can be connected to other function blocks locally or across the network. The user can write an expression (in a C-like syntax) in the NI-FBUS Configurator. The user then downloads the expression to the FP-3000, which executes it inside of an Expression Block. This makes the FP-3000 able to run custom embedded control applications.

Scheduling Functionality


Fieldbus networks require a Link Active Scheduler (LAS) to control communications on the Fieldbus. The FP-3000 can act as a primary or back-up Link Active Scheduler. This enables the FP-3000 to execute PID and other function blocks without a PC connected to the network. If a PC is connected and the PC goes down, the FP-3000 takes over the bus and executes the schedule.
Note: Disconnecting or crashing the PC while the PC's interface board is the LAS may cause a temporary "bump" in control, depending on the exact moment that the PC is disconnected. Users should consider making the FP-3000 their primary LAS to avoid this problem.

Hot Plug and Play (HotPnP)


FP-3000 network modules can be added or removed from H1 Fieldbus networks without affecting other Fieldbus devices.

Also, you can insert or remove I/O modules into FieldPoint terminal bases while the power is on, even if the FP-3000 is already operational. The other I/O modules connected to the FP-3000 are fully operational during this process. You do not need to power down the FP-3000, Fieldbus network, or even a bank to insert or remove I/O modules. You do not need to restart the host computer software to use the HotPnP feature. You can replace an I/O module only with another I/O module of the same type.

Note: Terminal bases on an FP-3000 are NOT hot-swappable (that is, they should not be added or removed except when the unit is not powered).
Related Links:
FieldPoint FP-3000 Network Module User Manual