Although the global market for I/O modules dropped by 15% between 2008 and 2009 – when it was worth $6.1bn – it is bouncing back. The market analyst IMS Research predicts that sales of PLC-based I/O will grow at an average of 8.9% a year over the period 2009–2014, while sales of PC-based I/O will exhibit a CAGR of 10.3% over this period.

PLC and PC I/O modules are used mainly in discrete industries and sales were hit badly by the recession, particularly in the automotive sector and machinery production. However, says IMS, these industries benefited from large government stimulus packages in the major industrial nations during 2009, and machinery production has been growing again since early 2010.  The PLC and PC-based I/O market is therefore likely to exhibit growth from 2010.
 
Although sales of DCS (distributed control system) I/O, primarily used in process industries, were not as badly affected as the PLC and PC I/O, the DCS market is not expected to pick up again until 2011. This is mainly because many process users plan investments more than a year or two in advance. The recession is therefore having a delayed impact on this market.
 
In addition, the growth impetus for DCS I/O is less than for PLC or PC-based I/O. Because sales of DCS systems are no longer driven by hardware product offerings, DCS products are being treated as commodities. Although there has been a growing emphasis on services across the automation market, this trend has been much stronger in the DCS world than in the PLC- and PC-based sector. As a result, IMS predicts that I/O modules controlled by DCS will be the slowest-growing market from 2009 to 2014.