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3.3 VLC-2-EIP Programming Guidelines
3.3.1 General guidelines
Provided the system macros in Appendix A have been loaded into the VLC, the acyclic and
cyclic objects (Tables 3.1 – 3.2) become accessible from the PLC. This allows the user to
perform the necessary servo parameter configurations through the acyclic objects and
monitor/manipulate the cyclic objects to execute motions following the instructions given
in the previous sections of this manuals.
Typically, a PLC program to control a VLC-2-EIP is built up based on the following sequence:
• Configuration of acyclic objects. These object values may be obtained from SMAC or
from a test that the user performed directly on the VLC (see section 2.2.1) or from a
test on the PLC.
• Motion initialization: phasing (for 3-phase actuators only) and homing.
• Main program task: this contains the logic to execute the required actuator motion
task that consists possibly of switching of modes of operation and coordination of
multiple axis that are connected to the PLC.
Given the above, there could be times when a failure associated with phasing/homing or a
VLC fault (servo error, general fault, see Table 3.3) occurs. Depending on the nature of the
motion task that the PLC is programmed for, the user may need to terminate the PLC
program execution and therefore special attention needs to be put on the statusword bits
(Table 3.3) associated with the failure/fault. When such event occurs, the next step is about
managing/clearing it, before resuming the PLC program execution.
3.3.2 Phasing/Homing management
Phasing and/or homing only needs to be executed once after the VLC-2-EIP is powered up.
The execution could be done through the PLC or automatically in VLC at power up, by adding
macros (refer to VLC-25-07 manual on programming the macros). In the latter case, the
macros can be added right after the execution of system macro 0 is completed. Make sure
that no MG command is used in the macros and note that phasing/homing done through
the macros will not update the success/failure execution status in the statusword (Table 3.3).
The subsequent PLC program action can be executed after statusword bit 0 (initialization
done) is set to ‘1’.
When phasing/homing is executed through a PLC, the user will be able to obtain the
success/failure execution status through the statusword. In most cases, a failed
phasing/homing is a result of an incorrect commutation and/or homing parameter or
parameters such as phase and sense setting (class ID: 0x6B, attribute ID: 0x2/0xA).
Furthermore, to perform homing, the position control parameters, for example proportional
and derivative constants have to be set. By setting the parameters correctly, possibly
obtained after a series of tests, phasing/homing can be executed again and the PLC program
can continue after the phasing/homing success bit in the statusword is set to ‘1’.
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