Global sales of PLC I/O modules have recovered well over the past two years, recording double-digit growth in both 2010 and 2011, according to a new report from IMS Research. However, recovery of the DCS (distributed control system) I/O market has been slower.

Industrial I/O modules can be split broadly into three categories by controller type – PLCs, DCSs and industrial PCs. The global recession from 2008 to 2009 hit the automation market hard, with sales of each type of controller falling more than 20%. The I/O market also suffered.

However, since 2010, sales of controllers and ancillary products have picked up substantially. “The entire I/O module market has benefited from the recovery of the controller market, especially that for PLCs,” reports IMS market analyst, Alex Hong.

The I/O module market grew by more than 20% during 2010, and by at least 10% more in 2011. The main driver has been a boom in machine-building.

Demand from the process automation sector has lagged, by comparison. Cash flows for process projects were cut off because of the recession, and this situation continued into 2011. Thus, the market for DCS I/O modules grew slower than that for PLC I/O modules. Because PLC I/O module revenues make up more than half of the total I/O module market, overall growth has remained strong.

“The I/O module market will benefit from a growing PLC market for the foreseeable future,” Hong suggests. However, he predicts that demand for DCS I/O modules will continue to lag behind.