July 2013 6.2 PLC axes 637
Module 9228 Coupling function for auxiliary axes
Module 9228 is used to enable/disable the coupling of auxiliary axes with other
auxiliary or NC axes for positioning movements. The resulting motions must
be defined in a formula (coupling function) for each coupled axis. This formula
is to be transmitted to the module as a PLC string.
Condition:
The arithmetic operations and trigonometric functions that can be used in a
formula are described in "Special case: Entering a formula" in the Machine
Parameters Chapter of the Technical Manual.
The coupling-function data is not forwarded until the PLC cycle has been
completed.
The status of a coupling function (readable with Module 9229) is available in
the subsequent PLC cycle at the earliest.
As long as the coupling function in the interpolator has not taken effect,
status module 9229 reports the status "0" for the coupling axis.
The coupling function can only be activated at standstill.
The axes must initially be positioned in such a way that the activation of a
formula does not result in a nominal-value step. Module 9229 (mode 1,
current nominal position with the help of a formula) is used to determine
whether the initial position of a coupling axis must be changed.
For the coupling functions (PLC module 9228), the resolution of the nominal
positions in the PLC module is 0.0001° or 0.0001 mm. The trigonometric
functions sin(), cos(), tan(), etc. require data input in radians (360° = 2*pi).
The inverse trigonometry functions supply the result in radians. To obtain
the radian values from the nominal positions in internal-resolution form, the
position value of the axis must be multiplied by pi / 1800 000 or in shorter
form by pi/18e5. Hence, the value of an inverse trigonometry function must
be multiplied by 18e5/pi to obtain the internal coordinate resolution.
The evaluation of W1022 is not necessary, because the error codes in the
return value make a detailed evaluation possible (see call interface).
The first PS during the module call must contain the string number of the
coupling function with the leading axis (NC/plc letter).
The second PS during the module call must indicate the axis index of the
auxiliary axis to be coupled.
Limit switches are not monitored for the coupled axis.
If there is an emergency stop and the machine is then switched on again,
the coupling is deactivated. The cancelation can be seen via status module
9229, feedback value 0 in mode 0.
Limit switches are not monitored for the coupled axis. The machine tool
builder must ensure that the coupled axis only moves within the
permissible area.
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