HEIDENHAIN PWM 20 - Manual (Page 200)

November 2014 Checking incremental encoders 203
6.3.6 Logic function, TTL
In the Logic function, the measured values are recorded at a very high sampling rate (200 MS/s).
However, no level measurement is conducted, but a logic analysis of the 1 and 0 signals instead.
The illustration shows the Logic screen with three display fields.
The coordinate axes show
X = Time in [ms], selectable through the number of periods
Y = Logic level (logical 1 or 0)
Note
For encoders with an interpolation >1, only the encoder properties and the minimum edge
separation are displayed after "automatic" connection. Other displays are suppressed, since
the interpolation would strongly falsify the calculation of on-to-off ratio, phase angle and
reference signal.
If the connection is effected with "manual settings", all displays are shown, as the ATS
software uses an interpolation of 1.
However, if the encoder interpolation is >1 nevertheless, the display values are incorrect!
Note
The logic function works up to a frequency <1 MHz and an edge separation > 20 ns.
The frequency is limited by the USB connection (PC - PWM 20).