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TA for use with Output Bypass Station to maintain outputs during maintenance operations  3-tier termination assembly for per channel internally and/or externally loop powered transmitters.  The FBM237 is electrically compatible with standard HART signals. REDUNDANT ANALOG OUTPUTS A redundant analog output function block, AOUTR, is used for each redundant pair of outputs. The AOUTR block handles output writes and initialization logic for the redundant channels. On each execution cycle identical output writes are sent to both modules, fully exercising the fieldbus and the logic circuitry of each module. When a failure is detected in one of the modules, its output is driven to 0 mA and the corresponding channel in the good module automatically continues supplying the proper current. Each output channel drives an external load. Transmitter power from each module is diode OR’d together in the redundant adapter to assure redundant power. The microprocessor of each module executes the analog output application program, plus security routines that validate the health of the module. Configurable options in the modules include Fail-Safe Action (Hold/Fallback), Analog Output Fail-Safe Fallback Data (on a per channel basis), Fieldbus FailSafe Enable, and Fieldbus Fail-Safe Delay Time. The Analog Output Fail-Safe Fallback Data option must be set for 0 mA output. This removes one of the pair of output channels from service for detectable problems such as a module not properly receiving output writes, or not passing security tests on FBM microprocessor writes to output registers. Setting of the Analog Output Fail-Safe Fallback Data option for 0 mA output also minimizes the possibility of a “fail high” result. PHYSICAL DESIGN FBM237 has a modular design, with a rugged extruded aluminum exterior for physical protection of the circuits. Enclosures specially designed for mounting the FBMs provide various levels of environmental protection, up to harsh environments (Class G3), per ISA Standard S71.04. HIGH RELIABILITY The redundancy of the module pair, coupled with the high coverage of faults, provides a very high subsystem availability time. Either module in the redundant pair may be replaced without upsetting field output signals to the good module. The module can be removed/replaced without removing field device termination cabling, power, or communications cabling. VISUAL INDICATORS Light-emitting diodes (LEDs) incorporated into the front of the module provide visual status indications of fieldbus module functions. FIELDBUS COMMUNICATION A Fieldbus Communications Module or a Control Processor interfaces to the redundant 2 Mbps module Fieldbus used by the FBMs. The FBM237 accepts communication from either path (A or B) of the 2 Mbps Fieldbus — should one path fail or be switched at the system level, the module continues communication over the active path. MODULAR BASEPLATE MOUNTING The module mounts on the Standard Modular baseplate, which accommodates up to eight Fieldbus Modules. The Modular baseplate is either DIN rail mounted or rack mounted, and includes signal connectors for redundant Fieldbus, redundant independent DC power, and termination cables. Redundant modules must be located in adjacent