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Migration Use of Termination Assemblies When an FBM217 is used to replace 100 Series FBMs, its associated termination assembly is determined based on which 100 Series FBM is being replaced. Typically, the 100 Series FBM being replaced was a main FBM and may have been used in conjunction with an expansion FBM. A single FBM217 provides the I/O communications for both the 100 Series equivalent main and expansion TAs. To provide enough terminals for the field input wiring, two termination assemblies are used with the FBM217 - one for the field input wiring for the replaced main FBM, and one for the field input wiring for the replaced expansion FBM. The “expansion” termination assembly is daisychained to the “main” termination assembly via the expansion cables listed in Table 3 on page 16. The table “FUNCTIONAL SPECIFICATIONS - TERMINATION ASSEMBLIES” on page 9 lists the termination assemblies needed to replace both the 100 Series main FBMs and the expansion FBMs. Alternatively, the FBM217 can accept field wiring through a Termination Assembly Adapter (TAA) instead of the termination assemblies when replacing 100 Series FBMs. This is discussed in Termination Assembly Adapter Modules for 100 Series Upgrade (PSS 21H-2W4 B4). 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. Low Voltage Discrete Inputs The low voltage inputs (less than 60 V dc) 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 V dc power supply to wet field contacts. A load may be required for proper operation of the input channels. High Voltage Discrete Inputs The high voltage input circuits support 125 V dc, 120 V ac, or 240 V ac. Voltage monitor inputs require a field voltage source. Some versions 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.