Siemens 6GK1970–5CA20–0AA2 Instructions De Montage page 374

Infrared Link Modul (ILM)
The "LOW" LED displays critical receive levels.
Minimum distance to
partner ILM 0.5 m
ILM
Figure 19: Transmitter Illumination of the PROFIBUS ILM
Copyright  by Siemens
Optical axis
12 m
15 m
50
6ZB530–3AC30–0BA1
2 m 4 m +/–10 degrees
aperture angle