Foxboro P0950CA Centralized and Distributed Control Module

Discrete Inputs

Various termination assemblies are available to support the interfacing of field signals

to the low level FBM input circuits. Active termination assemblies support input signal

conditioning for the FBM as well as channel isolation.

Be aware that for configurations which use main and expansion TAs, the I/O signal

conditioning circuits are designed to emulate the 100 Series FBM I/O subsystem. This

provides for functional I/O equivalence during upgrades from 100 Series to 200 Series

hardware.

The signal conditioning circuits are located on daughter boards that are mounted

under the component covers of the termination assemblies. To condition signals,

these termination assemblies provide optical isolation, current limiting, voltage

attenuation and optional terminal blocks to connect externally supplied excitation

voltage.

LowVoltage Discrete Inputs

The low voltage inputs (less than 60 VDC) use passive termination assemblies. Inputs

are voltage monitor or contact sense types. Voltage monitor inputs require an external

field voltage source. Contact sense inputs use the FBM auxiliary +24 VDCpower

supply to wet field contacts.

Aload may be required for proper operation of the input channels.

High Voltage Discrete Inputs

The high voltage input circuits support 125 VDC, 120 VAC, or 240 VAC. Voltage

monitor inputs require a field voltage source.

Someversions of the termination assembly have a pair of external excitation voltage

terminals, which distribute customer-supplied wetting voltage to all input channels on

the assembly. These terminals allow the field power to be daisy chained between

terminal assemblies