Mitsubishi Electric boosts MELSEC series

21 May 2009

Mitsubishi Electric expanded its MELSEC FX3 series of PLCs, releasing the FX3G, a compact controller for mechanical handling and plant engineering automation. It offers 128 I/O (expandable to 256 I/O with a serial network) and a powerful CPU.

The FX3 features a second system expansion bus and offers full migration and compatibility with the existing MELSEC FX series, so can simply be dropped into existing control systems. The new FX3G replaces the 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.

It boasts 0.21 microseconds processing per logical instruction cycle and 32,000 program step memory which, if required, allows it to utilise structured programming techniques to IEC 61131-3.

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 its 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 the PLC flexible.

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 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.

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 for simple programming. This allows speed and motion control tasks to be fully integrated with other control functions.

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