Foxboro FBM206 Pulse Input Module

Foxboro FBM206 Pulse Input Module

DESCRIPTION

The FBM206 contains eight pulse input channels, and the FBM206b provides four pulse input channels and four 0 to 20 mA analog output channels. Each input channel accepts a 2-wire, pulse input signal from a sensor. Input devices include vortex and turbine meters, solid state or electromechanical contacts, and other sensors with similar pulse outputs.

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

Features

• For the FBM206, eight 7 to 27 V dc, configurable, pulse input channels 

• For the FBM206b, four 7 to 27 V dc, configurable, pulse input channels and four 0 to 20 mA analog output channels 

• Each input channel accepts a pulse input with a maximum rate of 25 kHz 

• Each channel is galvanically isolated from the other channels and ground 

• Rugged design suitable for enclosure in Class G3 (harsh) environments 

• Execution of the pulse input application program with configurable options for Pulse Rate Totalization and Resolution (on a per module basis) and Meter Scaling Factor 

• Termination Assemblies (TAs) for locally or remotely connecting field wiring to the FBM206/206b 

• TAs for per channel internally and/or externally loop powered devices

Standard Design

The FBM206/206b module has a rugged extruded aluminum exterior for physical protection of the circuits. Enclosures specially designed for mounting the Fieldbus Modules (FBMs) provide various levels of environmental protection, up to harsh environments, per ISA Standard S71.04.

Fieldbus Communication

A Fieldbus Communication Module or a Control Processor interfaces the 2 Mbps module Fieldbus used by the FBMs. FBM206 accepts communication from either path (A or B) of the redundant 2 Mbps Module Fieldbus. If one path is unsuccessful or is switched at the system level, the module continues communication over the active path.

Functional Specifications

Input/Output Channels

• FBM206: 8 isolated independent pulse input channels 

• FBM206b: 4 isolated independent pulse input channels

Process I/O Communications:Communicates with its associated FCM or FCP via the redundant 2 Mbps module Fieldbus

Input Pulse Rate:10 Hz to 25 kHz

Input Channels (4 or 8):

• Accuracy: 

◦ Pulse Count: No missing pulses for pulse rate 10 to 25 kHz 

◦ Pulse Rate: 0.01% of reading, independent of rate 

• 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 Pulse Characteristics: See Figure 1 

• Input Duty Cycle: Minimum pulse width on/off (see Figure 1) 

• Input Channel Impedance: 10 kΩ 

• Loop Power Supply Protection: Each channel is channel-to-channel galvanically isolated, current limited, and voltage regulated. 

• Channel Power Supply Input: 24 V dc ±10% at 30 mA maximum to field device

Output Channels (4 -FBM206b Only)

• Output Range (Each Channel): 4 isolated independent 0 to 20.4 mA dc analog output channels 

• Output Load: 735 Ω 

• Compliance Voltage: 18.6 V nominal at 20 mA dc at I/O field terminals 

• Accuracy: ±0.05% of span (@25°C) 

• Output Temperature Coefficient: 100 ppm/°C 

• Communication: Via a redundant Fieldbus 

• Settling Time: 100 ms to settle within a 1% band of steady state for a 10 to 90% input step change. 

• Linearity Error: ±0.025% of span (monotonic) 

• Resolution: 12 bits

Power Requirements

• Input Voltage Range (Redundant): 24 V dc +5%, -10% 

• Consumption: 7 W (maximum) 

• Heat Dissipation: 5 W (maximum)