HEIDENHAIN iTNC 530 Service Manual page 284

A and B signal must be of equal size and move symmetrically around the same vertical axis (no
vertical offset)!
The 90° offset of the A and B-signal on the horizontal axis can be clearly seen.
A drop of the amplitudes during traverse could e.g. be an indicator for a contaminated scale
section. If the amplitude during standstill is too low, e.g., the scanning head could be
contaminated.
The signals in the integrated oscilloscope are always displayed in the unit mV, independent of
the type of encoder connected (1 Vpp or 11 µApp).
If you find that the sinusoidal signals have an offset (2.5 V) and do not correspond to 1 Vpp or
11 µApp, the signals must be converted using specified formulae.
18 – 284
Current signals Oscilloscope display [mV] / 284 = encoder signal at input [µA]
11 µApp: e.g.: 3124 [mV] / 284 = 11 [µA]
Voltage signal Oscilloscope display [mV] / 3480 = encoder signal at input [V]
1 Vpp: e.g.: 3480 [mV] / 3480 = 1 [V]
Now you can switch the oscilloscope display to XY (Lissajous figure):
HEIDENHAIN Service Manual iTNC 530