FOXBORO P0500WX Control System Module

The FBM217Discrete Input Module provides 32 input channels, each accepting a 2

wire input from a dc voltage source. Associated termination assemblies (TAs) provide

for discrete inputs of under 60 VAC, 120 VAC/125 VDC or 240 VAC. The module

performs signal conversion required to interface the electrical input signals from the

field sensors to the Module Fieldbus.

Depending on the type of I/O signal required, the TAs contain current limiting devices,

high voltage attenuation circuits, optical isolation and external power source

connections.

The module with its associated TA supports the following discrete inputs:

FBM

FBM217

30 VDC, 125VDC,120VAC,or240VACVoltage monitor or

Contact sense

The module can be used as a single unit, or as a redundant pair (two FBM217s).

Whenusedasaredundant pair, the modules combine to provide redundancy at the

Foxboro DCS Fieldbus Module (FBM) level, with field input signals received from one

commontermination assembly though a redundant adapter affixed to the FBMs’

baseplate. The field input current for redundant modules is doubled. A redundant

digital input block in the Foxboro DCS Control Software validates each input in

conjunction with information to/from the module, and selects the input with the highest

quality for processing in the control strategy.

In a redundant configuration, contact sense power from each module is diode OR’d

together in the redundant adapter to verify redundant power.

Aredundant contact input function block, CINR, is used for each redundant pair of

inputs. The CINR block handles input reads and initialization logic for the redundant

channels. On each execution cycle of the CINR block, identical reads are sent to both

modules, fully exercising the fieldbus and the logic circuitry of each module.

Whenconnected to the appropriate TAs, the FBM217 module provides functionality

formerly provided by the 100 Series FBM I/O subsystem. TAs are available which

support the functionality of the 100 Series main FBM07A/B, FBM08. FBM20. and

FBM24A/B/C (16 input main FBMs). Expansion TAs are available for use with these

main FBMTAsto support the functionality of expansion FBM12. FBM13. FBM21. or

FBM25A/B/C (16 input expansion FBMs)