AMCI SD4840EK, User Manual

Page: 25 / 104

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
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SD4840EK User Manual
M
OVE
P
ROFILES
25
Basic Move Types (continued)
Absolute Move
Absolute Moves move from the Current Position (A)
to a given position (B). (The SD4840EK calculates the
number of steps needed to move to the given position
and moves that number of steps.) A trapezoidal pro-
file is shown to the right, but Absolute Moves can also
generate triangular profiles. The command’s Target
Position can be in the range of ±8,388,607 counts. The
move will be clockwise if the Target Position is greater
than the Current Position and counter-clockwise if the
Target Position is less than the Current Position.
1) The
Home Position
of the machine must be set before running an Absolute Move. See refer-
ence 4,
Homing the SD4840EK
, which starts on page 49, for information on homing the
machine.
2) The Motor Position must be valid before you can use an Absolute Move. The Motor Posi-
tion becomes valid when you preset the position or home the machine.
3) Absolute Moves allow you to move your machine without having to calculate relative posi-
tions. If you are controlling a rotary table, you can drive the table to any angle without hav-
ing to calculate the distance to travel. For example an Absolute Move to 180° will move the
table to the correct position regardless of where the move starts from.
Controlled Stops

The move completes without error.

You toggle the Hold Move control bit in the Network Output Data. Note that your holding position will
most likely not be the final position you commanded. You can resume a held Absolute Move by using
the Resume Move bit or abandon the held move by starting a new one. The use of the Hold Move and
Resume Move bits is explained in the
Controlling Moves In Progress
section starting on page 35.
Immediate Stops

The Immediate Stop bit makes a 0

1 transition in the Network Output Data.

A inactive-to-active transition on an input configured as an E-Stop Input.

A CW/CWW Limit Switch is reached. If the limit that is reached is the same as the direction of travel,
for example, hitting the CW limit while running a CW move, a
Reset Errors
command must be issued
before moves are allowed in that direction again. If the limit that is reached is opposite the direction of
travel, a
Reset Errors
command does not have to be issued.
Figure R2.7 Absolute Move
SP
E
E
D
POSITION
A
B