FOXBORO FBM208/b, Redundant with Readback, 0 to 20 mA I/O Module

good module. The module can be removed/replaced without removing field device

termination cabling, power, or communications cabling.

Light-emitting diodes (LEDs) incorporated into the front of the module provide visual

indications of the module’s operational status.

Standard Design

FBM208/208b 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.

Fieldbus Communication

The Fieldbus Communications Module (FCM) or the Field Control Processor (FCP)

interfaces to the redundant 2 Mbps module Fieldbus used by the FBMs. The FBM208/

208b accepts communication from either path (A or B) of the 2 Mbps Fieldbus. If one

path is unsuccessful or is switched at the system level, the module continues

communication over the active path.

Modular Baseplate Mounting

The FBM208module mounts on aDIN rail mounted modular baseplate, which

accommodates up to four or eight FBMs. The FBM208b module also mounts on

conversion mounting structures. See 100 Series Conversion Mounting Structures

(PSS 41H-2W8).

Redundant modules must be located in adjacent positions on the baseplate, with the

first module located in an odd-numbered position (for example, the positions labelled

"3" and "4"). To achieve redundancy, a redundant adapter module is placed on the two

adjacent baseplate termination cable connectors to provide termination for a single

cable (see Figure 1. page 4). A single termination cable connects from the redundant

adapter to the associated termination assembly (TA).

Easy Removal/Replacement

Whenredundant, either module may be replaced without upsetting field input signals

to the good module. Each module can be removed/replaced without removing field

termination cabling, power, or communications cabling.

Redundant Modules in Foxboro DCS HMI

To system configurator applications and to other systems monitoring through SMON,

Foxboro DCS System Manager, and SMDH, redundant FBM208/208bs appear to be

separate, nonredundant modules. The functional redundancy for these modules is

provided by their associated control blocks.

Termination Assemblies

Field I/O signals for the FBM208 connect to the FBM subsystem via DIN rail mounted

termination assemblies (TAs). The TAs used with the FBM208 are described in

Termination Assemblies And Cables, page 13.

For field I/O signals for the FBM208b, see Use of Termination Assemblies in 100

Series Upgrade Subsystem, page 15.

Termination Assemblies And Cables

The FBM208field I/O signals connect to the FBM subsystem via DIN rail mounted

Termination Assemblies (TAs).

The redundant adapter connects the redundant FBMs baseplate input/output

connectors together. The redundant adapter provides a single termination connection

to a single TA (see Figure 1. page 4).

TAs are available in these materials:

• Polyamide (PA) material

The DIN rail mounted TAs connect to the redundant adapter by means of a removable

termination cable. The cable is available in a variety of lengths, up to 30 meters (98

feet), allowing the TA to be mounted in either the enclosure or in an adjacent

enclosure. Termination cables are available in these materials:

• Polyurethane

• LowSmokeZeroHalogen(LSZH