Ethernet TCP/IP for drive engineering

Building PLC functionality into drives is one way of meeting the requirements for integrated control. Jetter has taken the opposite approach, merging the drive system into the controller

For a long time, drive technology and control technology were considered independently. Hardware and software were separate. In this scenario, however, software and hardware interfaces have proved a handicap for programming, limiting options and performance.

A significant mark of the success of future control solutions is the integration of all controller functions, especially their handling. Drive technology plays a crucial role in this respect, due to its ever growing significance.

For this reason, manufacturers of drive systems integrate PLC functionality into their drive control systems. As a manufacturer of controllers, Jetter has gone the opposite way: the drive system is integrated into the controller in such a way that for the user there is no difference between programming PLC functions or drive functions. Networking by means of bus systems has by now become a pillar in merging drive and control - this is the case in the new JetMove servo system with Ethernet and distributed intelligence.

At an early stage, Jetter began to integrate all control functions logically into one system. Programmers of PROCESS PLC systems have just one programming tool and one programming language for control functions, drives and user guidance. There are no interfaces required between these functions. This makes programming a lot easier. The best example for this view of PROCESS PLC technology is the digital servo system DIMA - a controller for brushless servo drives. The system is logically fully integrated into the controller, so that real-time access is provided to all parameters of positioning, speed and current controllers. Start-up as well as programming has become significantly easier. The combination of control and drive functions in the program is a given. This affords interesting options, apart from simplified programming, which cannot usually be realised with many other systems without significant effort and expense.

The integration of all automation functions, made possible by a PROCESS PLC inside a controller, is expanded by JetWeb to integrate all systems throughout the entire production plant. Again, logical interfaces have been eliminated and integration has been advanced a great deal.

Distributed intelligence

JetWeb is based on the basic principle of distributed intelligence. Controllers, drives, user interfaces and intelligent sensors are able to communicate without hindrance and without hierarchies throughout a joint network. Current information (parameters and data) from any system is available to any other system in real-time. Consequently, a machine which is physically a combination of several intelligent de-centralised devices is logically considered a unit - as if it were a single controller.

All these functions are programmed by the JetWeb user with only one programming tool and one programming language. Unlike PROCESS PLC, even visualisation has now become a fixed entity of the JetWeb programming tool JetLab.

At the SPS/IPC/DRIVES Fair, Jetter AG introduced the latest generation of the digital servo system. The basic system can be used with PROCESS PLC technology, as well as with JetWeb. Differences between the two merely arise through differences in the equipment with intelligent sub-modules.

Physically speaking, the new servo drive system contains positioning, speed and current control, plus its own intelligence, which is especially significant in the context of JetWeb. Modularity is a crucial feature of this new drive system. Through a bus socket module, the user can choose for example between a resolver or a Hiperface transducer. While the resolver is lower in price and more robust, Hiperface has its own advantages:

• High position and speed resolution (32,768/rpm for position, and 1024x1024 for speed)
• Excellent response characteristics
• Automatic motor recognition
• Absolute encoder - no machine referencing required.

The conventional option of a 10V interface is also available.

Modular system

In respect of communication, the new DIMA/JetMove system has a lot to offer. The standard involves the trusted RS232 interface for display and diagnosis, as well as a CANbus interface. The controller can be expanded by modules through the Anybus socket, which makes it possible to implement various bus connections. For JetWeb, the most important one is of course the Ethernet interface with the IDA protocol.

In summary, the characteristics of the servo system JetMove are as follows:

• Built in intelligence for programs
• Automatic motor recognition
• Digital current, speed and position controllers can be individually parameterised and turned off
• Jerk, speed and current control
• Linear and sine square acceleration/deceleration ramps
• Automatic controller calibration
• Print mark recognition
• Electric gearbox and cam
• Winding function
• Flying saw.

Brushless drives ranging from 0.1 to 35Nm can be controlled by JetMove. Depending on the type, it is a single or three phase connection with 230 or 400V DC link voltage. The possible motor output ranges from 0.4 to 8.5kW.

If the system is used as JetMove in connection with the PROCESS PLC systems NANO and DELTA, communication is transparent, via the CAN system-bus interface. All parameters and data are available to the controller in real-time. Programming is done by means of the new programming surface WinSym and the clear-text programming language SYMPAS. This descriptive and process-oriented programming language contains commands for positioning tasks, too.

As a JetMove drive system, the digital servo controller is an intelligent node in the JetWeb network of distributed intelligence. In JetWeb, networking is accomplished by means of Ethernet TCP/IP. The JetWeb user realises all controller functions with the JetLab surface. Programming takes place in graphic flowcharts which can be expanded by textual programming. Here, too, pre-defined drive-specific commands and functions are available.

Jetter
g120@industrialnetworking.co.uk