GB2399238A

GB2399238A - A drive controller system

Info

Publication number: GB2399238A
Application number: GB0305264A
Authority: GB
Inventors: Peter Janicke; Tony Collins
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2003-03-07
Filing date: 2003-03-07
Publication date: 2004-09-08
Anticipated expiration: 2023-03-07
Also published as: GB0305264D0; GB2399238B

Abstract

The present invention relates to drive controller systems as used in machinery drive, for motor control and the like. In particular the present invention relates to a drive controller operator panel therefor. There is provided a method of operating a drive controller system comprising a drive controller having a removable operator panel, wherein the drive controller comprises a micro-processor having a memory operable to perform control of an associated drive wherein the operator panel is releasably connectable to the drive, comprising the steps of connecting the operator panel to the drive controller; and transferring data via a bi-directional 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-IC control. No process is required to change input data via an interface processor before data is transferred for processing in the operator panel.

Description

A DRIVE CONTROLLER SYSTEM

FIELD OF INVENTION

The present invention relates to drive controller systems as used in machinery drive, for motor control and the like. In particular the present invention relates to a drive controller operator panel therefor.

BACKGROUND TO THE INVENTION

In industrial plant, to enable machinery to operate, for example, a conveyor belt in a production line, pumps, compressors, ventilation systems, hoisting gear, cranes etc electric motors are employed. Electric motors may drive machinery directly by means of a clutch, by way of a transmission belt, hydraulic path, or some other means. The motor itself may drive a low wattage (less than 100W) application such as a drive for a laboratory centrifuge up to high wattage (greater than 300K\N) applications such as a steel press. The motors can be DC or AC, single phase or multiple phase. . À.....

Electric motors and other electrical devices are typically controlled by inverters which convert input power to variable voltage variable frequency for the motor or other electrical device. Inverters may be controlled by a control panel, serial communications protocol, or digital and analogue Input Output signals. In some cases optional modules can be fitted providing additional control possibilities. The inverters themselves are typically dimensioned as a rectangular box from smaller than 10 x 15 x 20 ems upwards, depending on power requirements.

It is normal for inserters to offer a user interface consisting of a display and keypad. Typically the display will be LED or LCD based, and may be purely numeric, or may include text display. These represent a significant cost of the inserters and are therefore often provided as a separate removable option. This provides a number of advantages. Firstly the cost of the operator panel need not be included in the cost of the drive. Many OEM applications use large numbers of drives where the operator panel is only required for commissioning and, subsequently, the drive is controlled by other - 2 means. In this case a single operator panel can be used for commissioning all the drives and then removed. An additional advantage in this case is that the drives may not be controlled by those not authorised. .These keypad/display unit controllers are of two main types: there is a low cost Basic Operator Panel (BOP) which provides a minimum of functionality and comprises of a simple keypad and display. Extra display elements may be used to indicate legends (amps, hertz, seconds, rpm, volts, percent etc) or leading half minus.

There is also another keypad - an Advanced Operator Panel (AOP) which often has a much easier user interface, comprising a full text and/or graphic display. These devices may also have additional functionality, such as simple automated control, or uploading and storage of drive configuration data. The cost of AOPs is approximately an order of magnitude greater than BOPs.

The interface is flexible to accommodate extra key switch options.

An additional function often required by users of drives is that of parameter cloning" Parameters within a drive are basically a set of configuration data that defines how a drive will operate. Examples of parameters could be Max Speed, Min Speed, Speed Ramp time, Drive..

control source, Motor data and so on. A typical drive can have hundreds of such parameters.

Users of drives are often manufacturing other products in which the À lo drives are a component. In this case, they want to be able to copy the parameter data from one drive to another drive (the two drives performing the same function in two different sets of equipment) - hence cloning" the functions and operating modes from one drive to another. This can be achieved by use of an operator panel. However, advanced functionality is required to allow the operator panel to read all the parameter data out of the drive, store it while it is moved from one drive to the next, and then download the data into the second drive.

Typically a simple form of a serial or parallel interface is used to communicate between the base drive unit and a removable operator panel. In order to keep the costs low for the operating panel, it is preferable that the power of the processor is minimised. The serial protocol consists of - 3 messages from the drive to indicate what should be displayed, and messages to the drive to indicate the state of keypad inputs. Known systems have a drive interface comprising a 4 way telephone- type sockethJack. The 4 can comprise: OV & 6.5V power supplies and Tx & Rx signals. The serial data communications to the drive can conveniently be RS232 level at 9.6 kbaud with 1 start bit, 8 data bits (Isb first), no parity and 1 stop bit.

Another problem associated with this type of system is that serial or parallel communications protocol associated with this is becoming less commonplace in point-to-point communications within an industrial premises: Communication systems which comprise a bi-directional 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control, like the Philips 12C _ communication bus protocol which were introduced around 20 years ago, are now firmly established as worldwide solutions for embedded applications.

Such buses are used extensively in a variety of microcontroller-based professional, consumer and telecommunications applications as a control, diagnostic and power management bus. Since these systems comprise a twowire serial bus, they are inherently simple in operation and comprise a simple bi-directional 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control. Such buses can support most fabrication processes and each device in a system can be identified by a unique address and can operate as either a receiver-only device e.g. an LCD driver or a transmitter with the capability to both receive and send information e.g. memory. Transmitters and/or receivers can operate in either master or slave mode, depending on whether the chip has to initiate a data transfer or is only addressed. These systems can also act as multi-master buses, i.e. they can be controlled by more than one IC. Data transfer rate up to 3.4 Mbits/s are possible with 7- or 10-bit addressing.

Despite the popularity of such bi-directional 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control systems, such systems have been viewed as being not sufficiently rugged for anything other than fixed applications. Moreover, typical low-cost processors have only two Universal Asynchronous Receiver Transmitters (UARTs). In these designs, the two UARTs have been employed on the one hand for communication with a power stack and, on the other hand, for a user interface, such as a RS485 interface. This has left no UART available for communication with an operator panel associated with a drive. Furthermore, where previous designs have included a processor with greater capabilities, an additional serial interface to the operator panel may have been used or, alternatively, a more expensive parallel interface to the operator panel would have been implemented. Another problem associated with this system of keypad controllers is that BOPs do not necessarily provide the required level of control to an operator yet the widespread distribution of AOPs to all levels of personnel within a associated with a drive system is prohibitively expensive and, furthermore, would enable unqualified personnel to affect production processes, unknowingly or otherwise.

OBJECT OF THE INVENTION

The present invention seeks to provide an improved drive controller operator panel and drive controller-operator panel system.

STATEMENT OF INVENTION

In accordance with a first aspect of the present invention there is provided a drive controller system comprising a drive controller having a removable operator panel, wherein the operator panel is releasably connectable to the drive controller, the drive controller and the operator panel being operably connected via a bi-directional 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control communications link, whereby segment and other data can be transferred directly to the operator panel display from the drive controller and switch and other data can be transferred directly to the drive controller from the operator.

The 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control communications link.can be in the form of an 12C communications link (Philips), or a microwire Bus (TM). - s -

No software has to be developed specifically for the operator panel to handle displaying of segment data and switch data as well as handling the serial protocol. As will be appreciated, this enables significant advantages, including cost to be realised. The system employs an interface already in the microprocessor eliminating the need to select a more expensive device with a 3rd UART (RS232 style serial interface) thus reducing cost in the drive.

There are LCD drivers and IO chips available which communicate directly on two wire serial data (SDA) and serial clock (SCL) bus, thus eliminating the need for a microprocessor in the operator panel. All the control can come from the drive. This significantly reduces the cost of the operator panel, and eliminates the need for a separate software development.

The interface has been made more rugged, suitable for use external of the drive by providing protection for both hardware and software from corruption caused by EMC and other issues (typically Electrostatic 1 5 discharge).

In accordance with a further aspect of the invention, there is provided method of operating a drive controller system comprising a drive controller À having a removable operator panel, wherein the drive controller comprises a micro-processor having a memory operable to perform control of an associated drive wherein the operator panel is releasably connectable to the. . drive, comprising the steps of: connecting the operator panel to the drive....

controller; and transferring data via a bidirectional 2-wire, serial data (SDA) and serial clock (SOL) bus for inter-lC control.

BRIEF DESCRIPTION OF THE FIGURES

The invention may be understood more readily, and various other aspects and features of the invention may become apparent, from consideration of the following description and the Figures as shown in the accompanying drawing sheets, wherein: Figure 1 shows a drive controller with an operator panel; and Figure 2 shows a hrst embodiment of the invention. - 6

DETAILED DESCRIPTION OF INVENTION i

There will now be described, by way of example, the best mode contemplated by the inventors for carrying out the invention. In the following description, numerous specific details are set out in order to provide a complete understanding of the present invention. It will be apparent, however, to those skilled in the art, that the present invention may be put into practice with variations of the specific.

Referring to Figure 1 there is shown an overview of a drive controller in operative association with an operator panel. Drive controller 2 has a main output O/P which is operable to control a drive and an interface 4 through which data is passed with respect to operator panel 6. The operator panel receives signals 7 from the drive relating to segment data which control those segments of the display to activate and feedback data relating to operation of the drive. The drive, in the case of a BOP will receive switch data 8 and will also receive, in the case of an AOP, parameter data - although this can also. . be transmitted by BOPs with memory. Drive controllers have been,.

connected, conveniently, by an RS485 or similar type of interface. This sort of system can provide remote drive control at distances of up 1000 metros.

The function of a drive can be considered to be simple, for example in. , 2 the case of conveyor belt at the start of a day a drive is switched on, the À..

speed increased to an operating speed and, at the end of the day, speed is reduced and the drive is switched off. However, for most industrial applications, this is not the case. In a manufacturing process, the use of a drive may be discontinuous and may be timed or be dependent upon another operation being completed. Different process steps could require different rates of increase in speed; frequency of operation may vary. Special features such as automatic restart following restoration of power subsequent to power failure may also be required. In addition different serial interfaces may be addressed e.g. RS485, RS232, USS Protocol and proprietary BUS/control systems e.g.. CAN-Bus (TM) etc. Depending on the type of motor concerned other operating variables susceptible to control comprise; frequency range e.g. 0-140 Hz, frequency resolution e.g. 0.1 Hz; temperature drift e.g. < 0.02% from lowest to highest frequency: linear or quadratic frequency characteristics; overload protection; overheating switch off; and many more.

Typically a simple form of a serial protocol is used to communicate between the base drive unit and a removable operator panel. In order to keep I the costs low for the operating panel, it is preferable that the power of the processor is greatly reduced. The serial protocol consists of messages from the drive to indicate what should be displayed, and messages to the drive to indicate the state of keypad inputs. Known systems have a drive interface comprising a four lead telephone-type socketack. The four leads can comprise: 0V & 6.5V power supplies and Tx & Rx signals. The serial data I communications to the drive can conveniently be RS232 level at 9.6 kbaud with 1 start bit, 8 data bits (Isb first), no parity and 1 stop bit.

One important use of the AOP is to transfer the operating parameters of a first drive controller to further drive controllers. This may arise, for example, following the successful testing of one drive whereby full scale production.... , using other drives is desired, or following the change in production...

requirements due to a change in type of product etc. An active memory! associated with the AOP is used to upload and store operating parameters from the memory associated with a first drive, which operational parameters, are then downloaded to other drives, when the AOP is disconnected from the....

first drive and attached to the other drives.

Referring now to Figure 2, there is shown an inverter or drive controller and a BOP 12. A bi-directional 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control, such as an 12C bus 14 is used to transfer data between the inverter and the BOP with a corresponding plug and socket (to I enable connection and disconnection of the BOP with respect to the drive, not shown) enabling control of the BOP to the drive. Normally non-default parameter values (known as "variable defaults) are stored in the parameter I EEPROM 16 resident on the inverter, the inverter EEPROM connected via a bi-directional 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control with an inverter processor 18. The BOP has a display, 20 a keypad/data entry means and a non-volatile memory 24. It is to be noted that this specific description that follows refers to an EEPROM in the BOP, but other types of non-volatile memory are equally suitable, such as a battery- backed RAM or a flash memory, although the description is not limited to these specific examples.

Using the BOP in accordance with one aspect of the invention, it is possible to done the parameters of one drive to another by firstly copying the non-default parameters from one inverter into the EEPROM resident on the BOP. Once copied, the BOP can be removed, attached to another inverter and then the parameter values copied from the BOP EEPROM into the inverter parameter EEPROM. The data is transferred from one EEPROM to the other by the processor over the bi-directional 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control which is also used to transfer push button strokes from the BOP to the processor and to transfer data to be displayed on the BOP LCD display. It will be appreciated, to simplify the use of software, that the format of the data on the BOP EEPROM is in the same format of the data on the EEPROM (parameter EEPROM) of the drive Accordingly, this same software can initialise the BOP EEPROM as the parameter EEPROM when copying the data from the BOP EEPROM to another drive. As there is no software present on the BOP, all that is required in hardware terms to achieve the cloning functionality is bi-directional 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control based EEPROM and the bi- directional 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control itself, the bi-directional 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control already being used for existing BOP functionality. Accordingly an extremely cost effective solution can be provided.

In operation there are simple operations procedures which are practiced to ensure positive instruction to drives. For example, there is a timeout period for the keypad. The timeout is set running by the transmission of a message and cleared by the receipt of a checked, valid message. It measures the time from start of message out to the return of a complete message. In normal - 9 - operabon the message response period should be much less than the timeout period for the bi-directional 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control runs at 100k baud on this application and the timeout for the keypad is 24ms. This is also bed in with a retry mechanism where on a failure to receive a message from the BOP, up to 3 more reads are carried out before determining that the BOP is no longer connected or has failed. It is to be noted that run and stop signals should be duplicated and inverted for integrity (redundancy). The software should also read a number of successive keystroke values and logically AND them before acting on the result. The BOP display is updated every ems. This helps to ensure that any spurious data sent to the display is overwritten very quickly as it is very unlikely that the data will be spurious on every update. When transferring data between the BOP EEPROM and the processor the data is verified and also has a checksum associated with it. This is done for reasons of data integrity.

Hardware protection can conveniently comprise of filtering components to prevent the sources of disturbance from damaging the bi-directional 2wire, serial data (SDA) and serial clock (SCL) bus components. Typical test procedures have included subjecting 8,000V discharges onto the interface pins). Additional integrity for the Run and Stop keys can be provided by transmitting both the normal, and inverted state of the switch to the drive That is to say, data is transmitted with redundancy: the data for these switches is transmitted twice, and the software checks to ensure that neither has been corrupted by interference - this is in addition to other checks that the software will make.

It will be appreciated that the cabling between an operator panel and a drive controller will contain at least four leads which will be served by corresponding plug and socket connectors. In the case of a bi-directional 2 wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control, there are at least 4 leads which comprise voltage supply leads and the two leads, SCL and SDA, for the bi-directional 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control. The invention thus provides a flexible interface - 10 between a remote mountable operator panel and an associated inverter or drive controller. À . À.a.. Àe À À- À À e e Àe À. À-.e À À.e. À e À À À. ee - 11

Claims

1. A drive controller system comprising a drive controller having a removable operator panel, wherein the operator panel is releasably connectable to the drive controller, the drive controller and the operator panel being operably connected via a bi-directional 2-wire, serial data (SDA) and serial dock (SCL) bus for inter-lC control communications link, whereby segment and other data can be transferred directly to the operator panel display from the drive controller and switch and other data can be transferred directly to the drive controller from the operator.

2. A system in accordance with claim 1 wherein the 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control communications link is in the form of an 12C communications link (TM),

3. A system in accordance with claim 1 wherein the 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control communications link is in À.

the form of a microwire Bus (TM).

4. A system in accordance with claim 1, wherein the operator panel is an.. '.: advanced operator panel, having an integral power supply and memory. .... À:::

5. A system in accordance with claim 1, wherein the operator panel is a basic operator panel.

6. A system in accordance with claim 1, wherein the operator panel is a basic operator panel which includes an EEPROM.

7. A method of operating a drive controller system comprising a drive controller having a removable operator panel, wherein the drive controller comprises a micro-processor having a memory operable to perform control of an associated drive wherein the operator panel is releasably connectable to - 12 the drive, comprising the steps of: connecting the operator panel to the drive controller; and transferring data via a bi-directional 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control.

8. A method in accordance with claim 7 wherein the 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control communications link is in the form of an 12C communications link (TM),

9. A method in accordance with claim 1 wherein the 2-wire, serial data (SDA) and serial clock (SCL) bus for inter-lC control communications link is in the form of a Microwire Bus (TM).

10. A method according to claim 7, wherein the operator panel is an advanced operator panel, having an integral power supply and memory.

11. A method according to claim 7, wherein the operator panel is a basic.. . . operator panel. ...

12. A method according to claim 7, wherein the operator panel is a basic operator panel which includes an EEPROM. . .

13. An operator panel operable in a system in accordance with claim 1.