TMCM-351 CANopen Firmware Manual - Trinamic

TMCM-341/342/343/351 CANopen Firmware Manual (V1.04 / 2011-AUG-01) 53
7.3 Homing mode
This clause describes the method by which a drive seeks the home position (reference point). There
are various methods of achieving this using limit switches at the ends of travel or a home switch in
mid-travel. Some methods also use the index (zero) pulse train from an incremental encoder. The user
may specify the speeds, acceleration and the method of homing.
There is no output data except for those bits in the statusword, which return the status or result of
the homing process and the demand to the position control loops.
There are four sources of the homing signal available: These are positive and negative limit switches,
the home switch and the index pulse from an encoder.
Figure 7.2 shows the defined input objects as well as the output objects. The user can specify the
speeds, acceleration and method of homing. There is a further object home offset, which allows
displacing zero in the coordinate system for the home position.
Controlword 6040h
Homing method 6098h
Homing speeds 6099h
Homing acceleration 609Ah
Home offset 607Ch
Homing
method
Copyright © 2011, TRINAMIC Motion Control GmbH & Co. KG
Statusword 6041h
Figure 7.2: Homing mode function
Position demand internal value 60FCh
or
Position demand value 6062h
By choosing a homing method, the following behavior is determined: the homing signal (positive
limit switch, negative limit switch, and home switch), the direction of actuation and where
appropriate, the position of the index pulse. The home position and the zero position are offset by
the home offset.
For the operation of positioning drives, an exact knowledge of the absolute position is normally
required. Since for cost reasons, drives often do not have an absolute encoder, a homing operation is
necessary. There are several application specific methods. The homing method is used for selection.