HEIDENHAIN TNC 150 B Mounting Instructions page 21

The TNC 150 is equipped with "software-limit switches".
The permissible travels of the machine axes are
programmed as machine parameters with reference to the location of the reference mark of the specific
transducer. (See "Software limit switch" , section 3.7 ).
After switching on the mains power of the TNC 150, the refl?rence points of all three machine axes must be
traversed over. After pressing the external Start-button, traversing over of the reference points is performed
automatically as per the entered machine parameters.
Please note: After entry of the code number 84 159 in the MOD-mode the reference points can also be traversed
over by means of the external direction buttons.
For location of reference points it is necessary for each machine axis to have a cam-switch ("Reference end
position"). The cam for this switch must be positioned such, that when travelling towards the cam, the switch
closes shortly before reaching the reference point and remains closed whilst still traversing in the same
direction until the emergency stop switch. A rotary table axis is an exception. For this axis, a permanent bridge
from J5/12 (TNC 150 B) or J4/9 (TNC 150 Q) to +24 V is required.
3.6.1 Location of "Reference end position" - cam when using linear transducers
(Inputs for "Reference pulse-inhibit" are not required and remain disconnected).
max. travel of axis
A--
Range between emergency stop
switches
II-
measuring length
al
Linear transducer
I
Reference point position
Cam switch "Reference end position"
closed
I
open
Switch "Reference end position"
3.6.2 Location of "Reference end position" and "Referenc:e pulse inhibit"
- cams when using rotary encoders
With installation of rotary encoders, an additional cam switc:h per axis is necessary for reference pulse
suppression.
A rotary encoder produces one reference pulse per revolution, e.g. a spindle pitch of 10 mm will, after 10 ms
of travel, transmit one reference pulse. The control will evalllate a reference pulse only when the cam switch
"reference end position" is closed and cam switch "reference
pulse inhibit " is open. In the example, the cam
must be adjusted such, that the switch opens 5 mm before tie desired reference pulse and closes approx. 5 mm
after the reference pulse.
max. travel of axis
Range between emergency stop
Lr switches
I 1
IA
A A
A L/\ =
I>
Possible reference pulses from
rotary encoder
desired reference pu Ise
Cam switch "Reference end position"
closed I
I
II
open
Switch "Reference end position"
I
' I
I 1
Cam switch "Reference pulse inhibit"
closed
closed
Switch "Reference pulse inhibit"
open
.I I
21