Adlink PCI-8158 Manuel d'utilisateur télécharger pdf (Page 53)

Operation Theory 43

A motion control system needs an absolutely real-time control

cycle and the calculation on controller must provide a control data

at the same cycle. If not, the motor will not run smoothly. This is

typically accomplished by using the PC’s computing power and by

a simple a feedback counter card and a voltage output or pulse

output card. This method is very low-end but requires extensive

software development. To ensure real-time performance, real-time

software will be used on the system. This increases the complexity

of the system, but this method is the most flexible way for a profes-

sional motion control designers. Most of these methods are on NC

machines.

4.1.5 DSP based motion control kernel

A DSP-based motion controller kernel solves real-time software

problems on computer. A DSP is a micro-processor and all motion

control calculations can be done on it. There is no real-time soft-

ware problem because DSP has its own OS to arrange all the pro-

cedures. There is no interruption from other inputs or context

switching problem like Windows based computer. Although it has

such a perfect performance on real-time requirements, its calcula-

tion speed is not as fast as PC’s CPU at this age. The software

interfacing between DSP based controller’s vendors and users are

not easy to use. Some controller vendors provide some kind of

assembly languages for users to learn and some controller ven-

dors provide only a handshake documents for users to use. Both

ways are not easy to use. Naturally, DSP based controller provide

a better way than software kernel for machine makers to build

applications.

4.1.6 ASIC based motion control kernel

An ASIC-base motion control kernel is quite a bit different than

software and DSP kernels. It has no real-time problem because all

motion functions are done via ASIC. Users or controller vendors

just need to set some parameters which ASIC requires and the

motion control will be done easily. This kind of motion control sep-

arates all system integration problems into 4 parts: motor driver’s

performance, ASIC outputting profile, vendor’s software parame-

ters to ASIC, and users’ command to vendors’ software. It makes

motion controller co-operated more smoothly between devices.

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Adlink PCI-8158 Manuel d'utilisateur Page 53