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4. CONTROL OF VIX DRIVES 45
4. Control of ViX Drives
Overview
This section introduces you to the operation of the ViX stepper drive, the implementation of
motion control moves and the way commands are used. Basic controller operation is
described together with the code structure. How system information is signalled via system
variables and the use of various flag registers for status and fault reporting are described.
Both basic and advanced motion control functions are covered including elements of event
driven code used for fault reporting and registration.
Controller Operation
ViX intelligent drives have an integrated controller which can be driven directly by a PC over
a serial link, or programmed to respond to code selected by event triggers or user
instructions.
Direct Mode
Direct operation of the controller over a serial link can be used for program
development/downloading purposes or direct on-line control from an industrial PC or PLC.
When used directly the controller will accept commands prefixed with the drive’s address
and will action the commands as they are received. In direct mode any controlling
application program is stored in a remote location and is only downloaded to the drive when
required.
Programmed Mode
This mode allows a program stored within the drive to control operations. The program can
be written off-line on a PC and then downloaded to the drive via a serial link. The application
program is stored within the drive and is automatically invoked at power up provided it is
enabled by the <a>ARM1X command and the program has a START label. Alternatively,
you could directly issue a <a>GOTO(START) command.
Code Structure
You write program code as a series of blocks. Each code block has a unique label at the
beginning and is terminated with an END label (block delimiter). The use of labels allows the
code structure of the form illustrated in Figure 4-1, which shows the block nature together
with an example of code.
Declare
Declare every label used in a program, apart from START, REG, NOREG and FAULT that
have been pre-declared. If a label is declared, but not defined, a runtime error will be
signalled when it is called.
Note: START, REG, NOREG and FAULT are all reserved labels.
You can only declare labels in the command line at the start of a program or within the
START code. The choice is between memory efficiency and the retention of declared labels