HEIDENHAIN PWM 20 - Manual (Page 147)

150 HEIDENHAIN ATS Software User's Manual
8 Click the button "Reference trigger on/off" to show the bar display for the
reference signal to the right below the bar display for the incremental signal.
Software connected to TTL square-wave output signal (description see section “Digital TTL/HTL
square-wave output signals” on page 196)