Controller/Drive 'Sandwiches' Eliminate Wiring, Saving Time and CostController/Drive 'Sandwiches' Eliminate Wiring, Saving Time and Cost

By "sandwiching" motor-drive amplifier boards onto a controller card, engineers at Galil Motion Control have eased assembly and eliminated often-complicated cable connections. A 96-pin DIN4162 AMP connector serves to directly connect the boards. The designers have also gained programming advantages with a hybrid analog/digital system.

The DMC-21x3 Ethernet controller half of the sandwich is a centralized multi-axis 32-bit device. The controller comes in one to eight axis versions and can be configured for stepper or servo control. Motion modes possible include positioning, jogging, interpolation (linear and circular), and electronic gearing. In addition to eliminating wiring, the multi-axis controller removes the need for the extensive software and time-intensive processing in a host computer in coordinating single-axis controllers over a distributed network.

The most recent amplifier boards to complete the sandwich can drive two or four stepper, brushed, or brushless motors of up to 500W. The AMP-20540 board with four PWM (pulse-width modulation) amplifiers measures just under 7 x 5 inches, accepts 18-60V dc, and produces 7A continuous current. PWM switching frequency is 60 kHz.

"The amplifier attached to the controller allows programming setup and diagnostics," says engineer and VP of Sales Lisa Wade. Thus working as a hybrid system with the controller, the amplifier handles the analog functions of closing the fast current loop and commutation while the digital controller allows diagnostics and tackles parameter changes. Such commands for the amplifier include Hall-sensor set up to ensure brushless phases are properly aligned, amplifier and current loop gain, and circuit protection functions. The latter include over current and voltage, short circuit, under voltage, and over temperature. However, Wade notes that multi-axis amplifiers are less flexible where different drive types and power are needed on each axis.

The controller and drive "sandwiches" work with servomotors from a variety of manufacturers. To aid users with motor selection, Galil has a series of application bulletins with the specifics of connecting the sandwiches to the motors. Go to www.galilmc.com/literature/technotes.html for more details. Galil Motion Control, www.galilmc.com Enter 692