Rockwell Automation 1746-BLM Blow Molding Module Installation Instructions - Manual (Page 17)

Blow-molding Module 17
Publication 1746-IN014B-EN-P - January 2001
Controlling Mandrel Position
Static Control: Mandrel position may be controlled statically with three axis-hold
values and corresponding hold-value control bits accessible via the module output
file. Hold values are prioritized with hold value #0 being highest, and hold value #2
being lowest. In time-based mode the hold values have no special interpretation.
In absence of an active profile, the highest priority enabled hold value becomes the
position setpoint.
Dynamic control: Mandrel position may be controlled dynamically by
downloading a setpoint profile to the module’s M0 file and setting the profile
enable bit. Then, upon receipt of an axis sync input signal, the module will
automatically update the mandrel position setpoint every millisecond until the
profile duration has expired or a new synchronization pulse is received.
Monitoring Mandrel Position
Instantaneous mandrel position may be monitored by reading the current process
variable from the module’s input file. Several other values are also available for
each axis (e.g. control output, profile step, etc.). Process variable profiles may be
read from the module’s M1 file.
Generating a Synchronization Signal
The module examines its digital inputs once every millisecond, so the minimum
pulse width (high or low) for external synchronization inputs is also one
millisecond. The module may also be configured via the G file to accept
synchronization inputs via its input file.
Modes of time-based operation
Fixed profile timing: For fixed profile times, the profile-time filter constant should
be set to zero. This way, the default profile time is used as the profile duration for
every profile, regardless of sync input pulse period.
Variable profile timing: The module may also be programmed to adapt to the
machine cycle time by setting the profile-time filter constant to values other than
zero. The programmed value enables a digital lowpass filter on the profile time
sequence. This has an effect similar to averaging previous profile times. Larger filter
time constants result in more filtering.