A new version of the “all-in-one”
motion-automation package by
Baldor Electric Co. expands control
for servo and stepper motors
from three to four axes. With its
onboard I/O and fieldbus connections,
the new NextMove-ESB2
servocontrol provides complete X,
Y, and Z along with Alpha-axis positioning
for material handling and
general machine control.
Real-time performance comes
from a DSP core. It supports servoloop
closure times of 100 μsec on
the four main axes, with six-term
closed-loop control for accurate
positioning with PID, velocity, acceleration
feed-forward, and velocity
feedback responses. A free
encoder input can be used as a
master axis. A typical application
for this feature is to let the servo
axes be programmed to perform
actions that follow the master at
some synchronized interval.
Four stepper axes provide pulse
and direction outputs at up to
500 kHz. Stepper outputs may also
control some servomotors depending
on the drives chosen. All in all,
the module can control up to eight
precision servomotor axes.
Onboard I/O lets users employ
the module for machine as well
as motion control — potentially eliminating the need for a separate
controller such as a PLC. The
I/O system has 20 digital inputs,
12 digital outputs, two 12-bit differential
analog inputs, a CANopen-
compatible fieldbus port,
and two serial ports including a
12-Mbits/sec USB interface.
The USB interface can be helpful
for automation OEMs that build
machines with PC hosts or user interfaces.
It lets the motion control
subsystem be panel mounted inside
the machine rather than residing
in a PC expansion slot.
The NextMove-ESB2 is programmable
using a special motion
language called Mint or in C. Mint
uses Basic-style programming with
keywords that handle many common
motion tasks from simple
profiles to advanced movements
such as software cams and flying
shears.
The Mint version supplied with
the NextMove-ESB2 includes a
multitasking kernel. This further simplifies development cycles by
dividing complex operations into
smaller tasks such as motion, manmachine
interfacing, and I/O handling.
The software is royalty-free.
For faster execution speed, there
is a free library of C-compatible
Mint functions that cover areas
such as motion control, I/O, communications,
networking, and
operator interfaces. The resulting
compiled code can take the form of
firmware that may then be embedded
in the controller, or called as
required from a host computer.
Motion interfaces may also be
created in any host environment
supporting ActiveX controls. The
ability to run Mint or C in parallel
with ActiveX provides support for
a wide range of widely used environments
such as Visual Basic.