Rockwell Automation 1746-BLM Blow Molding Module Installation Instructions - Manual (Page 16)

16 Blow-molding Module
Publication 1746-IN014B-EN-P - January 2001
Operation with an Auxiliary Position Input
This mode of operation lets you control four machine heads per 1746-BLM. Your
ladder program is responsible for calibration and scaling of process variable data
sent to the module via the output file. A value of -32768 corresponds to the
fully-forward ram position and +32767 corresponds to the at-shotsize ram position.
See page 12 for additional information on controlling with a separate, high-speed
analog module.
Step: 4 Module operation with a continuous extrusion machine
Time-based Operation
In time-based mode, setpoint profiles are specified as a function of the elapsed time
starting with the leading edge of the start-of-drop synchronization signal. Profile
duration may be held constant or derived from the time between previous sync
pulses. In either case, profile duration is divided into 256 segments.
When the elapsed time since the start of drop falls within the range of a particular
segment, the number of that segment is used as an index into the setpoint profile to
determine the current setpoint for the mandrel position. Should a new start-of-drop
synchronization pulse occur prior to completion of a profile in progress, a new
profile will be started. If the profile duration expires without receiving a
synchronization pulse, the last profile setpoint will be maintained indefinitely.
TIP Although you may specify profile sizes less than 256 in the
config file, the module expands these to 256-point profiles
after a download. Internally to the module, all profiles are 256
points in length. Similarly, process variable profiles are
compressed from the module’s 256-point internal
representation to your desired profile size prior to an upload.