FOXBORO FBM201 Analog Input MODULE

FOXBORO FBM201 Analog Input MODULE

Overview

The Compact FBM201 Analog Input Interface Module contains eight analog input channels, each channel accepting a 2-wire, 0 to 20 mA dc input from an analog sensor. It is part of the Compact 200 Series I/O subsystem described in Compact 200 Series I/O Subsystem Overview (PSS 41H-2COV).

The modules perform the signal conversion required to interface the electrical input signals from the field sensors to the FCP.

The FBM201 is electrically compatible with standard HARTsignals.

Features

• 8 channels for input of analog 0 to 20 mA dc sensor signals 

• Each analog input channel is galvanically isolated from other channels and ground 

• Compact, 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 integration time and 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 Compact FBM201 module 

• Termination Assemblies for per channel internally and/or externally loop powered transmitters

Compact Design

The Compact FBM201’s design is narrower than the standard 200 Series Fieldbus Modules (FBMs). It has a rugged Acrylonitrile Butadiene Styrene (ABS) 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 Accuracy

For high accuracy, the modules incorporate sigma-delta data conversion on a perchannel basis, which can provide a new analog input reading every 25 ms, and a configurable integration period to remove any process noise and power-line frequency noise. 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.

Easy Removal/Replacement

The module mounts on a Compact 200 Series baseplate. Two screws on the FBM attach the module to the baseplate. The module can be removed/replaced without removing field device termination cabling, power, or communication cabling

Functional Specifications

Input Channels (8)

• Analog Accuracy (includes linearity): ±0.03% of span Accuracy temperature coefficient: ±50 ppm/ºC 

• Field Device Cabling Distance: Maximum distance of the field device from the FBM is a function of compliance voltage (22.8 V dc), wire resistance, and voltage drop at the field device. 

• Input Channel Impedance: 61.5 Ω nominal 

• Input Signal A/D Conversion: Each channel performs A/D signal conversion using an independent Sigma-Delta converter. 

• Integration Period: Software configurable 

• Common Mode Rejection: >100 db at 50 or 60 Hz 

• Normal Mode Rejection: >95 db at 50 or 60 Hz 

• Loop Power Supply Protection: Each channel is channel-to-channel galvanically isolated, current limited, and voltage regulated. All analog inputs are limited by their design to less than 40 mA. If the current limit circuit shorted out, the current is limited to about 100 mA. 

• Input Channel Isolation: Each channel is galvanically isolated from all other channels and earth (ground). The module/TA withstands, without damage, a potential of 600 V ac applied for one minute between any channel and ground, or between a given channel and any other channel.