Positioning modes – Rockwell Automation 1771-QA Stepper Positioning Assembly User Manual User Manual
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Programming and Operation
Publication 1771-UM002A–EN–P – May 2000
In any mode, when the working moveset is finished, the storage
moveset automatically becomes the next working moveset. Then
another (storage) moveset can be block transferred to the stepper
positioning assembly.
In the continuous and independent modes of operation, the storage
moveset must be received by the stepper controller module before
the third from last move of the working moveset is complete (for
example, move 8 of 10 moves). In the single-step mode, the storage
moveset must be received before the second from last move of the
working moveset is completed. Skipped moves (section titled
“Move Block,” Bit 02) are not counted. The use of multiple
movesets allows long and complex positioning profiles or long
sequences of single moves to be performed with little additional
programming. The moveset is further defined in section titled
“Moveset Block.”
Positioning Modes
The stepper positioning assembly can be programmed for operation
that is tailored to the application requirements. The positioning
modes determine the type of positioning profile and the manner in
which the axes of two or three stepper motors can be coordinated.
The stepper positioning assembly can also be operated manually
using hardware or software jog inputs.
Single-Step Mode
In the single-step mode, a moveset allows the individual moves to be
controlled one at a time. A start command from the PC processor
starts the first move of the sequence. After the move is completed,
the stepper motor axis stops and a done bit is set. In order for the
next move to begin, the PC processor must transfer another start
command to the stepper controller module (Figure 3.2).
Figure 3.2
Single Step Mode
Time
Ramp
Decel
Decel
Ramp
Ramp
Decel
Final
Rate
Final
Rate
Final
Rate
Start
Command
Start
Command
Start
Command
Final
Position
Final
Position
Final
Position
Done Bit
is set
Done Bit
is set
Done Bit
is set
Move 1
Move 2
Move 3
Note: Jogging between moves causes a system fault..
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