SELECT AUTOMATIONS

PACs vs. PLCs

PAC            

Ø     Standard, commercial hardware             

Ø     Diverse protocols and open standards

Ø     Foundation of logic: exception based

Ø     Distributed processing

Ø     Common tag database

Ø     Multitasking

PLC

Ø     Proprietary network, communication, and programming

Ø     Programming and function are modeled after relay circuits

Ø     Ladder logic foundation

Ø     Continuous scanning

Ø     Mandatory duplication of data tags for interoperability