Programmable Logic Controllers Product Research, December 2007
Research was undertaken to gain a better understanding of Control Engineering subscribers’ applications and needs regarding Programmable Logic Controllers.
• Among those specifying, recommending, and/or buying Programmable Logic Controllers, 78% do so for inplant requirements, and 43% buy for OEM needs.
• Almost 40% of the average respondent’s installed PLCs are Micro PLCs (15 to 128 I/O points). Medium-sized PLCs (128 to 512 I/O) are installed by about one-third of respondents. In addition, 52% of PLC-type devices installed are considered embedded control with 35% mentioning PC-based devices (including PACs programmable automation controllers).
• Machine control is the most prominent application of PLCs at respondents’ locations. Process control is applied at about three-fourth of locations.
• Almost one in three respondents report having PLCs that act as stand-alone controllers, networked with personal computers, or are networked with other PLCs.
• Ethernet Protocol, Serial RS-232/RS-485, and 4-20 mA/0-10 V dc are currently the most widely used means of communication with PLCs.
• Among those who use Ethernet, 75% use it as a supervisory network, 70% for PLC-to-PLC networking with about half (53%) using it to control I/O connections. Among those who use Ethernet, 68% use EtherNet/IP as their protocol. TCP/IP is the second most popular protocol among this segment.
• Virtually all respondents use ladder diagrams to program PLCs. This is almost 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.
• Universal programming software for multiple hardware targets/platforms and PLCs with more remote I/O subsystems are the most anticipated features in future PLC purchases.
• Digital, analog, and communications are the most widely used I/O modules among those surveyed.
• Currently, the term PAC represents different things to different people. However, more than 40% of respondents are not currently using or considering PACs.
• Rockwell Automation tops the list of PLC manufacturers purchased from in the past 12 months. Virtually all of those surveyed are satisfied with their suppliers, with more than half being very satisfied.
• Fifty-two PLCs was the average number each survey participant purchased during the past 12 months. The average spending per respondent on PLCs in the past year was $38,000. 38% of respondents report their purchases of PLCs will grow in the next 12 months, while only 9% expect a decline.