Homing to limit switch

Even in simple applications which can be solved with the standard servo inverter 9300ES a homing function is often required which can evaluate limit switch signals. These homing modes are not supported by code C0932 in 9300ES, however.

In the default setting, 9300ES (standard servo inverter) only offers homing modes in the function block REF which allow an evaluation of homing labels, touch probe signals/zero pulse labels and a residual path processing. In many applications, homing to the limit switch with subsequent processing of a path offset is required. This performance can be achieved in the 9300ES servo controller by the attached function block connection.

The processing is as follows:

a) Homing is started with the signal 'Homing command' = HIGH and can be aborted any time (signal 'Homing command = LOW).

b) If the drive is not located on the limit switch (signal 'limit switch signal = LOW) the function block FLIP1 is set using the homing command. A fixed setpoint (in this example FCODE472/10) is provided as speed setpoint indirectly via the function blocks NOT2 and ASW1 (first homing phase = Moving towards limit switch with speed from code C0472/10).

c) If the drive reaches the limit switch (signal 'limit switch signal = HIGH) FLIP1 is reset via the OR1 link. This causes

d) The second homing phase is processed depending on the homing mode (C0932) set (= moving away from the limit switch with speed from C0935 and, if necessary, a path offset (code C0934) is processed).

Notes:
As the speed setpoint is switched over 'hard' via ASW1, this function block link is suitable only for low homing speeds. Normally, this homing performance is sufficient for the majority of applications. As a variant, the function block link can be used for 9300EK (servo cam).
Depending on the application, further abort criteria must be considered for homing (e.g. controller inhibit, quick stop,  ...).