Control Platforms Show Breadth

May 1, 2009
PLC Is Still Dominant, but PACs and PCs Have Their Admirers

The PLC is king of controllers for machine control platforms, but it’s not the only game in town. According to a recent Control Design survey, two-thirds of respondents said they primarily use PLCs. Both PACs and PC-based controls are each used by 13% of the participants in the survey. Embedded-board controls are used by only 5%.

Although PCs are receiving attention, 32% of the respondents who said they use PCs don’t use them for motion control. One-quarter of those same participants said they use PCs, but with an installed motion card, while 21% said they use PC-based controls only. The dominant operating system for these users is XP, selected by more than 77% of respondents. Other operating systems receiving mention included Vista, QNX, CE and even proprietary operating systems.

Surprisingly, 40% of surveyed PLC users aren’t using it for motion, but 30% do use it for all their motion control and 27% said they use it with a motion card connected.

The overwhelming language of choice was ladder logic, used by 87% of participants. Function block and structured text are used by 46% and 32% of respondents, respectively. Instruction list and sequential function chart each received 16% of the votes.

Sixty-one percent of the survey respondents said they use an integrated platform for which a single programming environment handles all required functions including control, HMI, I/O and motion.