AMCI SD4840EK, Руководство пользователя

Страница: 24 / 104

M
OVE
P
ROFILES
SD4840EK User Manual
ADVANCED MICRO CONTROLS INC.
24
Basic Move Types
Relative Move
Relative Moves move an offset number of steps (n)
from the Current Position (A). A trapezoidal profile is
shown to the right, but Relative Moves can also gener-
ate triangular profiles. The command’s Target Position
is the move’s offset. The offset can be in the range of
±8,388,607 counts. Positive offsets will result in
clockwise moves, while negative offsets result in
counter-clockwise moves.
1) You do not have to preset the position or home the machine before you can use a Relative
Moves. That is, the Position Invalid status bit can be set.
2) Relative Moves allow you to move your machine without having to calculate absolute posi-
tions. If you are indexing a rotary table, you can preform a relative move of 30° multiple
times without recalculating new positions in your controller. If you perform the same action
with Absolute Moves, you would have to calculate your 30° position followed by your 60°
position, followed by your 90° position, etc.
Relative Moves can be brought to a Controlled Stop by using the Hold Move Command from the network
data. When the command is accepted, the axis will immediately decelerate at the programmed rate and stop.
When stopped successfully, the SD4840EK will set a
Hold State
bit in the input data table. The Relative
Move can be restarted with the Resume Move command from the network data or the move can be aborted.
The Resume Move command allows you to change the move’s Programmed Speed, Acceleration Value and
Type, and the Deceleration Value and Type. The Target Position cannot be changed with the Resume Move
Command.
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 Relative Move by using
the Resume Move command or abandon the held move by starting a new one. The use of the Hold
Move and Resume Move bits is further 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 positive 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.
SP
E
E
D
POSITION
A
A+n
Figure R2.6 Relative Move