HEIDENHAIN PWM 20 - Manual (Page 189)

192 HEIDENHAIN ATS Software User's Manual
6.2.10 Checking homing/limit signals
In addition to the incremental graduation, encoders with position detection, such as the LIF 4x1,
feature a homing track for position detection (left/right) and limit switches for detection of limit
positions.
Example:
LIF 4x8R with limit plates
L (optical limit switches) and homing track H .
H is an additional scanning track dividing the scale into a left and a right half. The reference mark
is at the middle of the measuring length (in the picture, it is covered by the scanning unit).
The signals are transmitted in TTL level over separate lines. The trigger function can be tested
with the homing/limit function. The homing/limit function is activated when the encoder is
connected automatically via the ID of the scanning head.
In the images below, an LIF 481R with homing/limit signals serves as an example. Encoders with
limit switches (magnets) only are also possible.
8 After automatic connection via ID select the Homing/limit function.
8 Traverse the measuring range in both directions. Recording starts when the reference mark
(ML/2) is traversed. The homing and limit position values are determined and displayed.
Note
The homing/limit signals can only be tested, if the mechanical mounting is correct
and if the encoder was electrically adjusted according to its mounting instructions.