TMCM-142 TMCL
TM
Firmware Manual (V1.06 / 2014-JUN-24)
104
Copyright © 2009, TRINAMIC Motion Control GmbH & Co. KG
9.2
Reference search
The built-in reference search features switching point calibration and support of one or two reference
switches. The internal operation is based on three individual state machines (one per axis) that can be
started, stopped and monitored (instruction RFS, no. 13). The settings of the automatic stop functions
corresponding to the switches (axis parameters 12 and 13) have no influence on the reference search.
Right Stop
Switch
Traveller
Left Stop
Switch
Reference
Switch
Negative
Direction
Positive
Direction
Definition of the switches
Selecting the referencing mode (axis parameter 193): in modes 1 and 2, the motor will start by moving
left
(negative position counts). In mode 3 (three-switch mode), the right stop switch is searched first to
distinguish the left stop switch from the reference switch by the order of activation when moving left
(reference switch and left limit switch share the same electrical function).
Until the reference switch is found for the first time, the searching speed is identical to the maximum
positioning speed (axis parameter 4), unless reduced by axis parameter 194.
After hitting the reference switch, the motor slowly moves right until the switch is released. Finally the
switch is re-entered in left direction, setting the reference point to the center of the two switching
points. This low calibrating speed is a quarter of the maximum positioning speed by default (axis
parameter 195).
In figure 9.1 the connection of the left and the right limit switch is shown. Figure 9.2 shows the
connection of three switches as left and right limit switch and a reference switch for the reference
point. The reference switch is connected in series with the left limit switch. The differentiation between
the left limit switch and the reference switch is made through software. Switches with open contacts
(normally closed) are used.
In circular systems there are no end points and thus only one reference switch is used for finding the
reference point.
left stop
switch
right stop
switch
REF_L_x
REF_R_x
motor
traveller
Figure 9.1: Two limit switches
left stop
switch
reference
switch
right stop
switch
REF_L_x
REF_R_x
motor
traveller
Figure 9.2: Limit switch with extra
reference switch
motor
ref switch
eccentric
REF_L_x
Figure 9.3: Circular
system
