Rockwell Automation 1398-PDM-xxx IQ Master Version 3.2.4 for IA-2000 and IQ-5000 Positioning Drive Modules, IQ-55 - Manual (Page 181)

Motion • Step and Direction 159
Publication 1398-PM601A-EN-P — October 2000
TUTORIAL
no slew limit, the motor would attempt to accelerate up to the speed of the encoder instantaneously.
With a proper slew limit set, the motor will make a smooth acceleration up to the speed of the encoder.
Default values for SLEW and SLEWEN may be set in the Parameter menu, Velocity/Acceleration dia-
log box and changed at runtime. The following steps are required to set the ULTRA Plus or IQ to gear:
• In the Parameter menu, Feedback Configuration, dialog box select Encoder 2 IN. The Step and
Direction check box must be cleared to select Encoder 2 IN as they are mutually exclusive.
• If required, set (SLEW) and enable (SLEWEN)a slew rate limit. Default values may be set in the
Parameter menu, Velocity/Acceleration dialog box.
• Set (GEAR) and enable (GEAREN) the gear
Gear ratios may be modified while active by executing another GEAR command in the application pro-
gram or by using a Host Language Command. A motor will continue to gear to the encoder input after
the application program ends. To stop the gearing motion, you must execute GEAREN = OFF or disable
the ULTRA Plus or IQ.
In addition to standard gearing functions, there is also a function to limit the gearing motion in one
direction only. The TRACKINGMODEvariable is used to set up the type of uni-directional gearing. The
ROTT flag is used to set the direction, and the TRACKINGSYNCED flag is available to indicate
whether gearing motion is being presently limited by the tracking function. In addition, the TRACK-
INGEXTPOSSELECT flag is used to set whether the tracking function is applied before or after the
Gear and Slew functions.
Step and Direction
The ULTRA Plus or IQ can be set to follow step and direction commands entered through encoder 2,
similar to gearing. In this case, the GEAR sets the number of step commands per encoder count of
motion on the motor. The following steps are required to set the ULTRA Plus or IQ to follow step and
direction commands:
• In the Parameter menu, Feedback Configuration, dialog box select Step and Direction.
• If required, set (SLEW) and enable (SLEWEN) a slew rate limit. Default values may be set in the
Parameter menu, Velocity/Acceleration dialog box.
• Set (GEAR) and enable (GEAREN) the gear
Gear ratios may be modified while active by executing another GEAR command in the application pro-
gram or by using a Host Language Command. A motor will continue to follow step and direction sig-
nals after the application program ends. To stop this motion, you must execute GEAREN = OFF or
disable the ULTRA Plus or IQ.
Combination Motion
The motion that is commanded is the sum of the motion commanded from four sources, the profile gen-
erator, jogging motion, external sources and cam functions. The profile generator generates MOVD,
MOVP, DV and DIF moves. Jogging motion is created using the assigned jog inputs or MOVV com-
mands. External motion commands are the result of a gear or a step and direction command. Cam
motion commands are the result of executing cam profiles. An example of combination motion would
be a program that sets a gear so that a motor could follow an encoder. Once the gear is established, the
relative position of the motor to the encoder may need to be advanced or retarded. This can be accom-
Note: The SLEW limit remains active until it is shut OFF. If the acceleration rate of the master
encoder after the GEAR is greater than the SLEW limit, the acceleration of the follower will be lim-
ited to the SLEW limit. If this limit is exceeded, the follower will lose position lock with the master.