Potential-free contact (24 V/2 A) with socket to NAMUR NE 28, for signal generation, controlled by programme segment, for a total of 3 freely selectable functions to be activated (e.g. activation of audible and visual signals, exhaust motors, fans, stirrers, etc. (only for units with TwinDISPLAY), max 2 contacts for 1-ph. units, max 4 contacts for 3-ph. units,2 contacts.