Rockwell Automation has announced a new generation of modular micro-PLCs which can be tailored to suit the needs of individual machine control applications. With UK prices starting at around £50 for an eight-input, four-output version, the Micro800 PLC family will allow users to add plug-in modular components such as displays and communications, to achieve the performance and functions they need. Some models will offer three-axis motion control.

“We are delivering the functionality and flexibility of a micro-PLC for the price of a smart relay,” says Steve Pethick, director of Rockwell’s components and safety business in the EMEA region. He believes that the system’s greatest value will be “the simplicity and convenience it offers users – namely, that it offers ‘just enough control’. Users will only pay for what they need.”

Users can opt to use a blank version of the controller, or to pay an extra £30 for a screen which can also store and transfer programs to other controllers. The screen can be attached permanently or simply used as a low-cost way of transferring programs between controllers. Rockwell says that this option is not available elsewhere at this price.

“By offering multiple plug-in modules, we can help machine-builders change the ‘personality’ of the base controller to address a multitude of different bespoke scenarios and machine sizes,” Pethick explains. “This extra functionality is not at the cost of I/O terminals as the plug-in modules house their own connectors, leaving the base terminals untouched.”

A free program is available to program and configure the controllers. Called the Connected Components Workbench, it supports four IEC 61131-3 languages and can be used to configure other devices in a system, such as drives and HMIs.

In addition to the free software, which is expected to be sufficient for most applications, Rockwell is also offering a paid-for “Developer” version offering run-time downloads, offline controller simulation and advanced debugging.

The smallest member of the new controls family is the Micro810 controller, which has embedded smart relay function blocks and supports an optional 1.5-inch LCD and keypad. Even the basic 12 I/O version has 8A outputs, eliminating the need for external relays. DC versions allow four inputs to be used as 0–10V analogue inputs.

This will be followed later this year by 18 and 26 I/O versions with more memory (doubling the instruction capacity to 4k) and up to two slots for adding analogue I/O, serial ports and other plug-in modules.

The larger Micro830 model will handle up to three axes of motion and up to five plug-in modules (which can include a fourth axis). Single-axis moves will be supported by PLCopen motion instructions. These controllers will offer three pulse outputs and six high-speed counter inputs.

The largest member of the family, the Micro850, will have embedded Ethernet I/P communications to link it to drives, HMIs and PCs. It will support up to four I/O expansion modules.