Programmable Logic Controllers Product Research (November 2006)

Research was undertaken to gain a better understanding of Control Engineering subscribers’ applications and needs regarding Programmable Logic Controllers.

By Control Engineering Staff December 14, 2006

Research was undertaken to gain a better understanding of Control Engineering subscribers’ applications and needs regarding Programmable Logic Controllers.

Executive Summary

• Among those specifying, recommending, and/or buying Programmable Logic Controllers, 78% do so for in-plant requirements and 47% buy for OEM needs.• A little over one-third of the average respondent’s installed PLCs are Micro PLCs (15 to 128 I/O). Medium PLCs (128 to 512 I/O) are a close second.• Machine control is the most prominent (83%) application of PLCs at respondents’ locations. Process control is applied at about three-fourth of locations.• Almost one in three respondents report they have PLCs that are networked with other PLCs, networked with personal computers, or are used in stand-alone applications.• Serial RS-232/RS-485, Ethernet Protocol and 4-20 mA/0-10 V dc are currently the most widely used methods of communication with PLCs.• Among those who use Ethernet, 74% use it for PLC-to-PLC networking with about the same, 72%, using it as a supervisory network.• Among those who use Ethernet, 71% use TCP/IP as their protocol. EtherNet/IP is the second most popular protocol among this segment.• Virtually all respondents use ladder diagrams to program PLCs. This is more than double the usage of any other programming language.• Built-in communication support is the most important feature to survey participants when buying a programmable logic controller CPU.

Programmable Logic Controllers Product Research 2006