It's easier to understand and evaluate a new technology if you can see how its capabilities compare with technologies you already know. This chart compares features of a PAC with those of PLCs, DCSs, PCs, and RTUs.
| Feature |
PCs |
PLCs |
RTUs |
DCSs |
PACs |
| Industrially hardened hardware |
|
x |
x |
x |
x |
| Discrete control/sequential control |
|
x |
x |
|
x |
| Process control (batch and continuous) |
x |
x | |
x |
x |
| Remote monitoring & control, SCADA |
|
x |
x |
|
x |
| Motion control |
x |
|
|
|
x |
| Multi-domain capabilities (One controller performs logic, process control, discrete control, motion control, monitoring, and data acquisition.) |
x |
|
|
|
x |
| Distributed control functions to reduce load on central controller (examples: PID loop control, pulse generation, latching, events and alarms) |
|
|
|
x |
x |
| Critical local operations continue in the event of a communication failure. |
|
|
|
x |
x |
| Multifunction (Meet complex requirements without add-ons or middleware.) |
|
|
|
|
x |
| Multitasking |
x |
|
|
|
x |
| Efficient processing and I/O scanning (PACs scan only when logic requires it, thus reducing data polling and network traffic.) |
x |
|
|
x |
x |
| Data-intensive applications such as recipe or batch processes; recipe switching |
x |
x |
|
x |
x |
| Floating-point math |
x |
x |
|
x |
x |
| Compact, high-density system |
|
x |
|
|
x |
| Flexible, modular architecture (Use same hardware in small or large system; easily expand system with additional modules.) |
|
|
|
|
x |
| Extensive communication options |
x |
|
x |
|
x |
| Open languages and standard protocols |
x |
x |
|
|
x |
| Open, standard network interfaces |
x |
|
|
|
x |
| Easy support for multiple vendors' hardware & software |
x |
|
|
|
x |
| Integrated hardware and software |
|
|
|
x |
x |
| Integrated development environment for all applications (Discrete, analog, serial, motion, etc. Reduces programming effort/time.) |
|
|
|
|
x |
| Common tagname database (No retyping or cross-reference lists.) |
|
x |
|
|
x |
| Long, plain-language tagnames |
|
|
|
|
x |