Getting your move on

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.