HEIDENHAIN PWM 20 - Manual (Page 20)

August 2014 Overview of cables and adapters 21
3.1.1 Feed-through operation (listening-in)
"Feed-through" operation means connecting the PWM 20 into the control loop of
an NC-controlled machine tool.
For diagnosing, the PWM 20 can be integrated into the control loop of an NC controlled
machine tool via adapter cables at the encoder input X1 and the encoder output X2.
For the feed-through mode the power supply must be switched to the subsequent electronics
in the ATS software.
Set the checkmark in feed-through mode only.
If no subsequent electronics is connected, the encoder is not powered (error message).
The feed-through mode is supported as of the software version 2.6. We recommend always
using the most recent software version (see www.heidenhain.de).
The feed-through mode cannot be used for all interfaces supported by the ATS.
In principle, the following interfaces allow for the loop-through mode:
EnDat, Fanuc, Mitsubishi, 1 Vpp, TTL, 11 µApp
EnDat / Fanuc / Mitsubishi
 Metallic isolation is possible with the service adapters SA 100 and SA 110.
 No metallic isolation, if the measurement is conducted with the PWM 20 only.
 For encoders that also support incremental signals, the incremental signals can now also be
displayed and evaluated.
Note
Determine the IDs of the encoders on the machine axes before you configure the feed-
through mode.
NOTE: For this purpose, the PWM output must not be connected to the control!
If the PWM output is connected to the control, the terminating resistors disturb the
measuring functions of the PWM.