Rockwell Automation 1398-PDM-xxx IQ Master Version 3.2.4 for IA-2000 and IQ-5000 Positioning Drive Modules, IQ-55 - Manual (Page 409)

Application Examples • In-line Bottle Filler 387
Publication 1398-PM601A-EN-P — October 2000
APPENDIXES
encoder and master encoder. The scale parameter should be set for each encoder according to the
machine mechanics. For example, if the leadscrew pitch is 5 revolutions per inch, and the encoder on
the controlled axis has 8,000 pulses per revolution, then the SCALE parameter for the motor encoder
(encoder 1) is 8,000 x 5 = 40,000 counts per inch. The scale factor for the master encoder on the
machine is entered in the SCALE2 parameter in counts per user unit.
The ABSOLUTE mode parameter should be turned on. The ULTRA Plus or IQ controller will not allow
absolute moves (MOVP) to execute until a home position is established to insure that the lead screw
mechanism is operating within the travel limits.
The VELOCITY parameter must be high enough so that when the filling operation is completed the fill-
erhead can return to its home position before it needs to begin tracking the next batch of bottles. The
velocity feedforward gain (KFF parameter) is used to reduce the following error and is entered in per-
cent. The velocity feedforward gain can improve following error while gearing, but can also cause the
system to overshoot during incremental moves.
The fillerhead must operate within the travel limits of the lead screw. Hardware limit switches should be
used to protect the machine and personnel. The LIMIT inputs parameter enables or disables the forward
and reverse limit switch inputs (input 1 and input 2). For additional protection, the FORWARD LIMIT
and REVERSE LIMIT parameters set software limits so that system operation will halt and a fault will
occur if the fillerhead reaches one of these limits. Position limits are defined within the program to exe-
cute a programmed action such as stopping the fill operation if these limits are exceeded. A forward
position limit can be defined in a scanned event within the program. The scanned events allow certain
conditions to be detected without requiring the use of program statements to poll for their occurrence.
When the event is detected, a programmed action is executed.
The In-Position WINDOW parameter should be set to relative, so that the In-Position output will be
activated anytime the system is within the In-Position window, even while in motion. The In-Position
Window defines the maximum position error that is considered in position.
Sensor Placement & Wiring/Registration
The fillerhead home sensor should be wired to the Home Switch input (Input 5). The Home Switch
Active parameter selects the home switch input as active open or active closed.
The bottle sensor should be placed so that when the sensor reads the leading edge of the last bottle to be
filled in that sequence, the fillerhead nozzles are approximately over the opening of each bottle. A soft-
ware offset variable can be used to fine-tune the target position. The program assumes consistent spac-
ing between bottles and waits for the proper distance to pass based on the master encoder before the
interrupt is enabled to capture the last bottle to be filled in that sequence. It is also possible to have the
sensor detect each bottle and then wait for the correct number of bottles to pass before tracking. The
bottle sensor is wired to an interrupt input (Input 11) for maximum accuracy and fastest response. The
interrupt inputs are edge triggered. Sensors with sinking outputs (NPN) should be used. The interrupt
input latches the position within 50 microseconds of the off to on transition of the sensor. There will be
a slight error in position due to this delay. The program calculates this error and executes a move to cor-
rect the error.