FOXBORO FBM216b Redundant HART® Communication Input Module

FOXBORO FBM216b Redundant HART® Communication Input Module

DESCRIPTION

The FBM216b HART Communication Redundant Input Interface Module contains eight individually isolated input channels. It supports any mix of standard 4 to 20 mA devices and HART devices (the signals are electrically compatible). A pair of modules combines to provide redundancy at the fieldbus module (FBM) level, with field inputs wired to one common termination assembly (see Figure 1, page 4). In this configuration, one FBM216b is the Master, and the other is the Tracker. The FBM216b can serve as a HARTcommunications field device host, enabling Foxboro™ DCS to request and receive two digital messages per second from the field device. The message pass-through capability can be used to support HART universal, common practice, and device-specific commands, but it cannot support the burst communication mode. These commands are implemented using the Foxboro DCS Field Device Expert for HART. For details, see Field Device Expert for HART Devices Control and I/O (PSS 41S-10FDMHRT). The FBM216b provides individually isolated power supplies to power each of the eight channels.

Features

• 8 individually isolated analog input channels. Each channel accepts one of the following inputs: 

◦ Standard 4 to 20 mA analog sensor signal 

◦ Digital HART Frequency Shift Keying (FSK) signal superimposed on a 4 to 20 mA analog signal 

• Module pair offers redundancy at the FBM level 

• FSK modem dedicated to each input channel for bi-directional digital communications with a HART field device 

• Analog to digital conversion of each of the 4 to 20 mA input signal from the HART devices 

• Support for the HART universal commands necessary to interface the field device with the Foxboro DCS database 

• Per channel galvanic isolation of each of the eight input channels from each other, ground and module logic 

• Rugged design suitable for enclosure in Class G3 (harsh) environments per ISA Standard S71.04 

• High accuracy achieved by sigma-delta conversions for each channel 

• Termination Assembly (TA) for locally or remotely connecting field wiring to the FBM216b 

• TA provide for per channel internally and/or externally loop powered transmitters

Functional Specifications

Field Device Channels

• Supported HART Instrument Types: HART instruments compliant to Version 5, 6, or 7 of the HARTspecifications may be used 

• Interface: 8 individually isolated channels 

• Communication to the Device: Point-to-point, master/slave, asynchronous, half-duplex, at 1200 baud 

• Error Checking: Parity on each byte, and one CRC check byte 

• Speed: 2 messages per second • Fastest Allowed ECB Block Period: 100 msec - However, it is recommended that you refer to the Sizing Guidelines and Excel Workbook appropriate for your Control Processor to determine the optimal loading for a 100 msec Block Processing Cycle (BPC). 

• Maximum Distance (FBM216b to Field Device): Meets HART FSK physical layer specification HCF_SPEC-54, Revision 8.1 [up to 3030 m (10000 ft)](a) 

• Internal Loop Supply Compliance Voltage at Termination Assembly: 18.5 V dc minimum at 20.5 mA 

• Current Inputs: 

◦ Sense Resistor: 280 Ω ± 0.02% ◦ Total Input Resistance Including Redundancy Adapter: 280 Ω nominal ◦ Analog Accuracy (included Nonlinearity): ± 0.075% of full scale 

◦ Temperature Coefficient: 50 PPM/°C 

◦ Resolution: 15 bits 

◦ Update Rate: 100 ms 

◦ Integration Time: 500 ms 

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

◦ Normal Mode Rejection: >35 db at 50 or 60 Hz

• Loop Power Supply Protection: Each channel is individually galvanically isolated, current limited and voltage regulated. All field connections are limited by their design to less than 37 mA with a single module installed (72 mA when redundant modules are installed). 

• I/A Series®/Control Core Services: Requires I/A Series software v8.2 to v8.8 or Foxboro DCS Control Core Services v9.0 or later. 

• Input Resistance Including Termination Assembly and Redundancy Adapter: 

◦ Externally Powered: 282 Ω 

◦ Internally Powered: 302 Ω 

• FBM Internal Power for Field Device: Per channel isolated 24 V dc ±10% supply. Loop supply output impedance is 20 Ω including the termination assembly.