5.        Multiple-level alarm priorities

6.        Continuous self-tuning capability

7.        Multiple-loop control capability

8.        Provisions for simple interlocking

9.        User-defined algorithms

10.     Adaptive control

11

.     Hard-Manual control station

12.     Cascade control

13.     Multiple-configuration memory storage and recall

14.     Feed forward capability

15.     Removable configuration modules

16.     Fieldbus communications capability

17.     Fuzzy logic capability

In 2003

1.        PID capability

2.        External communications capability

3.        Adaptive control

4.        User-initiated self-tuning

5.        Provisions for simple interlocking

Source: 2005 and 2003 research from Control Engineering and Reed Research Group

Even when loop controllers stand alone, communications rate high among priorities for subscribers surveyed in 2005. In 2003, leading priorities for stand-alone loop controllers were similar, except for adaptive control, which rated significantly higher two years ago.