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Technical Discussion: Mitsubishi’s Next Generation Of Factory Automation

11 August 2008

This article is for readers who want more specialised in-depth information from an engineer’s perspective on Mitsubishi Electric’s iQ platform. This section describes the positioning of the iQ Platform, its technical overview, and the specifications and characteristics of the compatible products. For links to related articles, see the end of this article.

Mitsubishi
Mitsubishi

Evolution: Four-in-one

Sequence, Motion, NC and Robots are unified into one controller.

The iQ Platform has come.

1. PREFACE

Currently, production lines in the semiconductor, liquid crystal, and automotive manufacturing sectors are faced with accommodating production of multiple models in varying amounts, rapid accommodation of shortening product cycles, and improving production efficiency. Mitsubishi Electric has made production line visualisation a reality, working under the concept of the FA unification solution e-F@ctory, which optimises the entire factory, as shown in Figure 1. Mitsubishi Electric’s MES Interface products are on the market as a solution for seamless data interconnection between higher order information systems and the production line. Now, in addition to this data interconnection, we are unveiling the iQ Platform, a production line interconnection solution which radically resolves various issues for the production line, from the perspective of Total Cost of Ownership.

2. IQ PLATFORM, PRODUCTION LINE INTERCONNECTION SOLUTION

Factory production lines are facing ever-increasing demands for improved productivity, improved manufacturing quality, reduction of development costs required for configuring or changing a line, reduction of startup costs, and reduction of maintenance and operation costs. To respond to these demands, Mitsubishi has developed products based on the iQ Platform, a new concept that optimises the production line by strengthening interconnection between FA products used on the production line. The iQ Platform product line is shown in Figure 2.

2.1 IQ PLATFORM COMPATIBLE CONTROLLER

Demand is strengthening for the production line to have higher speeds and larger capacity for data transmission as the production becomes more sophisticated and complex. In response, the conventional System-Q CPU performance and inter-CPU bus performance were improved, and we developed an iQ Platform compatible controller well-suited for high speed and large capacity data.

2.1.1 CONVENTIONAL PLATFORM

The sequencer (System-Q) uses the building-block method for configuring a control system, in which the user inserts required units (CPU, power supply, I/O, intelligent function, network, etc.) into slots, depending on the purpose and scale of equipment use. Also, the conventional System-Q multi-CPU system (can install a maximum of four CPU units) shares a system bus as shown in Figure 3, and uses a bus arbitration method in which each CPU monopolises the bus while it accesses the I/O unit or network unit.

2.1.2. CONTROLLER PLATFORM

The issue was that the conventional system bus alone would form a system performance bottleneck when the performance of each CPU improved. So, a multi-CPU high speed bus and synchronisation system was developed as a controller platform, having the following characteristics.

(1) MULTI-CPU HIGH-SPEED DATA TRANSFER

With the multi-CPU high speed bus, the CPUs share a high speed memory with a 14k word capacity, as shown in Figure 5. When using a system with two CPUs, this is 3.5 times the capacity of the conventional System-Q shared memory (Figure 3). The multi-CPU high speed bus transfers this 14k word data at a specified cycle. This is about 8 times the speed of the inter-CPU data transfer using the conventional Q series system bus. The newly developed multi-CPU high speed base unit is configured so that this multi-CPU high speed bus and the conventional System-Q system bus coexist (Figure 4). This enables continued use of the nearly 100 types of various units (I/O, intelligent function, network, etc.) in the System-Q series.

4 controllers on one platform prototype
4 controllers on one platform prototype

(2) DATA TRANSFER SYNCHRONISED WITH MOTION CONTROLLER CALCULATION CYCLE

The motion controller, synchronised with servo motor control, performs calculations at a specified cycle (0.44msec, 0.88msec, 1.77msec, etc.). The multi-CPU high speed bus data transfer is executed at a specific cycle (0.88msec), synchronised with this motion controller calculation cycle. This accomplishes optimum data transfer between the CPUs, and raises the total performance of the system (for example, a system comprising a sequencer CPU and motion controller CPU). This works similarly for the CNC for the line and for robot controllers.

(3) INTERRUPT SEQUENCE FUNCTION SYNCHRONISED WITH MOTION CONTROLLER CALCULATION CYCLE

An interrupt sequence was developed for the high speed sequencer CPU, which is executed and synchronised with the motion controller calculation cycle. This enables high speed response motion control, independent of the sequence program scan time.

2.1.3 HIGH SPEED SEQUENCER CPU

The high speed QnU series improved the PCMIX value (index of sequence control performance) by about 6 times the conventional value, by increasing the speed of basic command processes and floating decimal calculations, and increasing the memory access speed. Also, the file register capacity built into the CPU unit was expanded by about 6 times the conventional amount, enabling high speed processing of large capacity data. In addition, the program file storage count in the program memory was expanded to twice the amount, simplifying program structuring and creating program parts.

2.1.4 HIGH SPEED MOTION CONTROLLER CPU

A new hardware architecture was developed for the high speed motion controller Q17nD CPU, doubling the processing capacity compared to the conventional model. For example, when performing six axis control with servo motors, the motion controller calculation cycle of 0.88msec has been accelerated to 0.44msec, which enables high speed response and shortens cycle time. Also, the motion SFC processing performance has improved about four times over the conventional model.

2.1.5 CNC CPU FOR THE LINE

Again a new hardware architecture was developed for the control unit Q173NC CPU , also known as CNC C70 series (for production and transfer line applications), which was compatible with System-Q. The installation footprint was reduced to about 45% of the conventional size, and the processing capacity was improved to about double the original capacity. Also, compared to conventional models, the nearly 100 types of additional units from System-Q can be used, enabling flexible system configuration to accommodate the system content and system size. Furthermore, the large screen and highly expandableGOT1000 can be used for the display, simplifying creating various system operating screens.

2.1.6 ROBOT CONTROLLER CPU

New hardware architecture was also developed, again compatible with System-Q, for the MELFA SQ series robot controller Q172DR CPU, improving the processing capacity to approximately double the conventional capacity. Again, compared to previous models, the ability to use the nearly 100 types of existing System-Q units enables flexible system configuration. In addition, signal-related wiring (up to a maximum of 256) has been completely eliminated.

2.2 HMI GOT1000 SERIES

The HMI GOT1000 series has expanded its various conventional functions to accommodate the new iQ Platform compatible products. In particular, functional expansions of the circuit monitor function, Q motion controller monitor function, line CNC monitor function, data I/O function, and backup/restore functions have improved line side work efficiency (startup, maintenance, etc.) in a multi- CPU system.

Mitsubishi iQ platform
Mitsubishi iQ platform

2.3 CONTROLLER NETWORK

The controller network CC-Link/IE was developed to improve total system performance. CC-Link/IE introduces communication technology into its physical layer meeting the IEEE 802.3Z (1000BASE-SX) standard, increases communication speed to 1Gbps, and expands the number of link register points to eight times the number in MELSECNET/H (Mitsubishi Electric’s previous high speed controller network). The link scan time, which is equivalent to data transfer time, has been decreased to about 14 times our previous speed (70msec to 5msec), when using a 32 unit configuration (with 2k points per station). That means, iQ Platform compatible controllers can perform high speed control within each device, and the entire production line is optimised by strengthening interconnection between devices using the controller network.

2.4 IQ PLATFORM COMPATIBLE ENGINEERING ENVIRONMENT

Conventional control systems performed engineering work such as programming and debugging using individual software for each machine. However, as the control system becomes more complex, it becomes vital to improve software interconnection for improving engineering work efficiency. Therefore, Mitsubishi plans to improve the software interconnection and improve engineering work efficiency by developing and subsequently releasing an iQ Platform compatible engineering environment.

3. FUTURE PLANS

In the future, Mitsubishi Electric will continue to improve the product lineup and common functions of controllers, HMI, networks, engineering environments, etc., based on the iQ Platform concept. This in turn will continue to promote improved production efficiency on production lines, reduction of engineering costs, and provide revolutionary streamlining of the development environment for the user.

This material was prepared by Kumio Saito, Controller Planning Group Manager, Development Division, Nagoya Works, Mitsubishi Electric Corporation.

The September 2008 issue of Control Engineering Europe, has an article beginning on page 8, “Mitsubishi puts four controllers on a single platform.” The story discusses Mitsubishi Electric’s new iQ platform, which combines four different controller types—the PLC (programmable controller), CNC (computer numerical control, used for automated machine tools), motion control, and robot control. To view this news story online, CLICK HERE.

Control Engineering Europe presents an informal discussion of Mitsubishi’s development engineers as they talk about the iQ platform. To go to the discussion CLICK HERE


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