Beckwith Electric M‑2025B Current Loop Interface Module: This device accepts

the current loop output and properly scales it by the use of an external resistor.

It also is configured by a jumper to select a unipolar or a bipolar current loop

input. It provides an analog voltage output to the M‑2001 Series Control that

tracks the analog current output of the Tap Position Monitor.

The lowest analog dc voltage corresponds to the lowest tap position number

and the highest dc voltage corresponds to the highest tap position number. 

Tap Position Monitor: This device compares voltages from the stator windings

of the Selsyn transmitter to determine the rotor position.

The position information is converted to a tap position number and is usually

displayed on the front of the unit. This device includes an analog current output

that corresponds to the displayed tap position.