If you've got the time, we’ve got the motion card.

Until about ten years ago, there were two primary motion controller types. The first is shown in Figure 1, and is called a multiaxis motion card. In this architecture, the motion card connects to external amplifiers, which accept +/- 10V analog signal input, and control torque or sometimes motor velocity. Today’s motion cards are available in a variety of interconnect formats including PCI, PC/104, compact PCI, and Ethernet.

Motion cards have a number of advantages, primary among them flexibility. Since the interface format to the amplifier is standardized, different motor sizes, and even different motor types, can easily be changed as the application evolves. This means that if the user changes the power of the motor, or the motor type, the motion card doesn't need to be changed, only

Multi-axis motion card

the amplifier. Another important advantage of motion cards, particularly multi-axis motion cards, is that synchronization is automatic. Control is usually all under one DSP or microprocessor “roof,” so axes servo at exactly the same frequency.

A disadvantage of this architecture is wiring complexity and cost. Servo motors can have as many as twenty five wires per axis to carry signals such as encoder feedback, Hall-sensors, etc. If you are constructing a system with more than a few axes, this can quickly add up to thick cables, and a servicing nightmare.