FOXBORO FBM216 HART® Communication Redundant Input Interface Module

FBM216 HART® Communication Redundant Input Interface Module

The FBM216 offers redundant modules for eight input channels, each accepting a 4 to 20mA analog signal

or a digital HART® signal superimposed on a 4 to 20 mA analog signal.

FEATURES

Key features of the FBM216 module are:

Eight analog input channels, each accepting one

of the following inputs:

• Standard 4 to 20 mA analog sensor signal

• Digital HART Frequency Shift Keying (FSK)

signal superimposed on a 4 to 20 mA analog

signal.

Module pair offers redundancy at the FBM level

FSK modem dedicated to each input channel for

bi-directional digital communications with a

HART field device

Analog to digital conversion of each of the 4 to

20 mA input signal from the HART devices

Support for the HART universal commands

necessary to interface the field device with the

I/A Series® system database

Galvanic isolation of the group of 8 input

channels from ground and module logic

Compact, rugged design suitable for enclosure in

Class G3 (harsh) environments

High accuracy achieved by sigma-delta data

conversions for each channel

Termination Assemblies (TAs) for locally or

remotely connecting field wiring to the FBM216

Termination Assemblies for per channel internally

and/or externally loop powered transmitters.

OVERVIEW

The FBM216 HART Communication Redundant

Input Interface Module contains eight group-isolated

input channels. The FBM216 supports any mix of

standard 4 to 20 mA devices and HART devices.

A pair of modules combines to provide redundancy

at the Fieldbus Module (FBM) level, with field inputs

wired to one common termination assembly (see

Figure 1). In this configuration, one FBM216 is the

Master, and the other is the Tracker.

The FBM216 serves as a HART communications field

device host, enabling the I/A Series system to

request and receive two digital messages per second

from each field device. The message pass-through

capability can be used to support HART universal,

common practice, and device-specific commands,

but not the burst communication mode. These

commands are implemented using the Intelligent

Field Device Configurator (IFDC — refer to PSS

21S-8A2 B3 for details).

The FBM216 provides a common isolated power

supply to power all eight channels. Optionally, the

channels can be powered by an external power

supply, in which case a Cable Balun module is

required to prevent channel crosstalk.

HIGH ACCURACY

For high accuracy, the module incorporates a Sigma

Delta converter which can provide new analog input

values for each channel every 100 milliseconds.

COMPACT DESIGN

The FBM216 has a compact design, with a rugged

extruded aluminum exterior for physical protection of

the circuits. Enclosures specially designed for

mounting the FBMs provide various levels of

environmental protection, up to harsh environments

per ISA Standard S71.04

HIGH RELIABILITY

The redundancy of the module pair, coupled with the

high coverage of faults, provides very high

subsystem availability time.

Either module may be replaced without upsetting

field input signals to the other module. A module can

be removed or replaced without removing field

device termination cabling, power, or

communications cabling.

REDUNDANT ANALOG INPUTS

For each input operation, identical reads are sent to

both modules, fully exercising the Fieldbus and the

logic circuitry of each module. Each input channel

accepts an analog sensor input or a self-powered

4 to 20 mA source. Device power from each module

is diode OR’d together in the redundant adapter to

ensure redundant power.

The microprocessor of each module executes the

analog I/O application program, plus security routines

that validate the health of the FBM. Input channel

security is enhanced by redundantly powering the

input current loop from per-channel power supplies in

each module of the pair.

VISUAL INDICATORS

Light-emitting diodes (LEDs) incorporated into the

front of the module provide visual indication of the

module’s operational and redundancy status, and

communication activity on the channels. Two

additional LEDs provide the master or tracker status

of the modules.

FIELDBUS COMMUNICATION

A Fieldbus Communication Module or a Control

Processor interfaces the redundant 2 Mbps module

Fieldbus used by the FBMs. The FBM216 module

accepts communication from either path (A or B) of

the redundant 2 Mbps fieldbus – should one path fail

or be switched at the system level, the module

continues communication over the active path.

The use of an external power supply common to two

or more loops requires a Cable Balun module to

maintain communication signal line balance.

MODULAR BASEPLATE MOUNTING

The module mounts on a modular baseplate which

accommodates up to four or eight FBMs. The

modular baseplate is either DIN rail mounted or rack

mounted, and includes signal connectors for

redundant fieldbus, redundant independent dc

power, and termination cables.

Redundant modules must be lo

CABLE BALUN MODULE

The Cable Balun module is used to maintain digital

communication line balance for HART Transmitter to

FBM loops that are powered from a common

external power supply. This powering effectively

connects one line of each loop together. Without the

Baluns, in each loop so powered, the common

connection at the external power supply, would