FMM-101 is a miniature monitor module (a mere 1.3" (3.302 cm) H x 2.75" (6.985 cm) W x 0.5" (1.270 cm) D) used to supervise a Class B (Style B) circuit of dry-contact input devices.
With 4 independent amplifier channels (100 V), the 4XD125B is compatible with the Variodyn D1 system and controlled by its DOM4-8 or DOM4-24. The NF inputs and control inputs are connected to the DOM