Mitsubishi Electric has expanded its MELSEC FX3 series of PLCs with the FX3G, a compact controller for mechanical handling and plant engineering automation, offering 128 I/O (expandable to 256 I/O with a serial network), a powerful CPU and easy configuration through clip-on application modules. Like all of Mitsubishi’s third generation controller series, the FX3 features advanced new technologies, including a second system expansion bus. Of maximum importance to plant engineers and business owners and in line with Mitsubishi’s design policy with regard to legacy systems, it offers full migration and compatibility with the existing MELSEC FX series, so can simply be dropped into existing control systems.
The FX series is the world’s most successful line of compact controllers with over nine million units sold over the last 30 years. The original FX caused a sensation; as it lead to the demise of the individual hardwired relay as the base unit of control system engineering, it opened up whole new horizons for control and automation of production plant in many many industries.
The new FX3G replaces the popular FX1N, resetting the cost-performance expectation with a larger program memory, faster instruction execution, additional programming instructions and improved functions and expansion options. Particular advances have been made in communication and positioning functions, the seamless integration of other control devices and networking options.
In keeping with Mitsubishi’s policy of maximum usability, the FX3G is based on the same space-saving technology concept as the more powerful FX3U and
FX3UC, which are designed for high level and demanding automation tasks. All the necessary components – including power supply unit, processor, memory and I/Os – are integrated directly in the ready-to-use controller units.
It’s 0.21 microseconds processing per logical instruction cycle and 32,000 program step memory enables it to handle significant automation tasks and opens up the possibility, if the user desires, to fully utilise structured programming techniques to IEC 61131-3. Compared to the original FX1N, of course, this is unbelievable performance which would have been available only through larger modular system solutions.
In addition to the standard system bus for up to eight expansion, special function and network modules, the new controller also has a second bus system like it’s bigger brother the FX3U. Up to four additional modules – two interface modules (RS-232 or RS-485) and two analogue adapters, including a new temperature data acquisition module for Pt1000 and Ni1000 elements – can be connected to this “adapter bus”, making this compact PLC extremely flexible.
The new adapter bus modules were developed specifically for the FX3 family, with modern technology that make them very compact. They can be integrated without additional programming and can be addressed directly with special data registers. In addition to reducing the number of program steps needed this also saves time and money. Additional expansion slots are available on the front of the unit, where up to two expansion boards can be inserted to add serial communications interfaces (RS-232, RS-422 or RS-485) and analogue functions.
The new controller is programmed with the GX Developer or GX IEC Developer programming software package. This supports the IEC 61131-3 standard and program development with the function block, ladder diagram, instruction list, structured text and sequential function chart languages. The programming instruction set includes both basic instructions and over 120 dedicated application instructions, making both programming and system configuration fast and simple.
Expansion options
The FX3G is in 14, 24, 40 and 60 I/O versions. Power supply is 100-240V AC for international deployment, with a 24V DC version to follow for specialist deployments. All output types are available in digital relay and transistor versions, and all base units can be expanded to up to a total of 128 I/O with additional modules and up to 256 I/O via open fieldbus networks.
A display module that plugs into the front panel of the base unit provides quick information. Important controller data can be displayed and edited with the help of four function keys. A two-level keyword protection system with separate sets of access permissions for users and developers ensures that only authorised personnel have access to the controller program.
With communications and networking becoming ever-more important, the FX3G supports Profibus, CC-Link, Ethernet, and CANopen, plus data communications via up to three serial interfaces. A USB port and an RS-422 port come integrated in the front panel. Other connections can be implemented with interface modules.
FX3G can adopt either a slave or master status on the CC-Link network. The ability to become a CC-Link master means that it can integrate to the Mitsubishi CC-Link Safety Relay which manages basic safety functions like emergency stop, light curtains and other safety devices and gives the user the added benefit of networked safety diagnostics back at the FX3G PLC.
For positioning, the new PLC has six high-speed counters supporting frequencies of up to 60kHz. There are also pulse outputs for frequencies of up to 100kHz for controlling up to three independent stepping or servo motors. Direct connection is also available for up to eight variable speed drives with dedicated instructions to make programming quick and easy. This allows speed and motion control tasks to be fully integrated, at low cost, with other control functions.
In summary the new MELSEC FX3G controller adds an economical solution for standard mechanical handling and plant engineering applications to the Mitsubishi MELSEC PLC range. It is an ideal platform for building customised lower and mid-range automation solutions. And can seamlessly integrated with the larger iQ Automation Platform series.