FOXBORO FBM202 Thermocouple/mV Input Module

FOXBORO FBM202 Thermocouple/mV Input Module

The FBM202 Thermocouple/mV Input contains eight thermocouple input channels, and one isolated RTD

reference junction compensation channel.

OVERVIEW

The FBM202 Thermocouple/mV Input contains eight

thermocouple input channels, and one isolated RTD

reference junction compensation channel (for terminal

temperature sensing). Each thermocouple/mV

channel accepts standard thermocouples for various

temperature ranges, and each provides

thermocouple burnout detection (up-scale). The

inputs are galvanically isolated from other channels

and ground.

The module performs the signal conversion required

to interface the electrical input signals from the field

sensors to the optionally redundant Fieldbus. It

executes an Analog Input application program, which

provides integration time and Rate of Change Limits

configurable options

Two types of passive termination assemblies are

available for the FBM202:

 DIN rail mounted TAs, similar to those used with

the other 200 Series FBMs

 Baseplate-mounted TA, which mounts directly

onto the field I/O connectors of the 200 Seriesbaseplate. These TAs provide field I/O wiring

support for two FBM202s in paired slots (that is,

in positions 1 and 2. 3 and 4. 5 and 6. or 7 and

8), as shown in Figure 1

When connected to the appropriate TAs, the

FBM202 module provides functionality formerly

provided by the 100 Series FBM I/O subsystem. TAs

are available which support the functionality of the

100 Series FBM02.

FEATURES

Key features of the FBM202 are:

 Eight channels for input of thermocouple signals

 One isolated RTD reference junction

compensation channel (for terminal temperature

sensing)

 Each input channel is galvanically isolated

 Rugged design suitable for enclosure in Class G3

(harsh) environments

 Execution of an analog input application program

that provides conversion time and configurable

options for Rate of Change Limits

 High accuracy achieved by sigma-delta data

conversions for each channel

 Termination Assemblies (TAs) for locally or

remotely connecting field wiring to the FBM202

HIGH ACCURACY

For high accuracy, the module incorporates Sigma

Delta data conversion on a per-channel basis, which

can provide new analog input readings every 25 ms,

and a configurable integration period to remove any

process noise and power line frequencies.

Each time period, the FBM converts each analog

input to a digital value, averages these values over

the time period and provides the averaged value to

the controller.

STANDARD DESIGN

FBM202 has 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.

VISUAL INDICATORS

Red and green light-emitting diodes (LEDs)

incorporated into the front of the module provide

visual status indications of the FBM operational

status.

EASY REMOVAL/REPLACEMENT

The module can be removed/replaced without

removing field device termination cabling, power, or

communications cabling.

FIELDBUS COMMUNICATION

A Fieldbus Communications Module or a Control

Processor interfaces to the redundant 2 Mbps

module Fieldbus used by the FBMs. The FBM

accepts communication from either path (A or B) of

the 2 Mbps Fieldbus — should one path fail or be

switched at the system level, the module continues

communication over the active path.

MODULAR BASEPLATE MOUNTING

The module mounts on a DIN rail mounted

baseplate, which accommodates up to four or eight

Fieldbus Modules. 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.

TERMINATION ASSEMBLIES

Field I/O signals connect to the FBM subsystem via

a:

 DIN rail mounted TA, or

 Baseplate-mounted TA.

The TAs used with the FBM202 are described in

“FUNCTIONAL SPECIFICATIONS – TERMINATION

ASSEMBLIES” on page 8