CLIAMS:We Claim:

1. A method for optimization of input and output data transfer during profibus cyclic communication in a networked computerized industrial process control systems, the method comprising:
• connecting a relay with a computer using a communication module with a configuration utility ;
• selecting parameters (required by a PLC master device) in the relay using configuration utility, wherein the PLC master device is capable of communicating with the relay;
• selecting a bit information (required by a PLC master device) in the relay using configuration utility, wherein the bit information is changed by any one of clubbing required information and discarding the useless bytes;
• Configuring the relay as per data sequence and selection, wherein the relay is configured by using any one of adding multiplication factor in current value of the parameter and sending only useful bytes of the parameter in a PLC register;
• Configuring the PLC registers as per memory map selection;
• Configuring the PLC master device with previously used .GSD file and Reading/writing operation with maximum data utilization.

2. The method of claim 1, wherein the communication module is Modbus.

3. The method of claim 1, wherein the parameter of the PLC device is selected from any one of ID, Size (length of parameter), multiplication factor and any bit information.
,TagSPECI:Field of the invention

The present invention relates to a networked computerized industrial process control systems and, more particularly, relates to a method and system of optimization for input or output data transfer during profibus cyclic communication.

Definitions

PROFIBUS (Process Field Bus) is a standard for fieldbus communication in automation technology.

GSD files– GSD file contain information about the basic capabilities of a device. All devices are shipped with a GSD file, or a file can be downloaded from this web site or the vendor's own web site.

Background of the invention

PROFIBUS DP is a network that is made up of two types of devices connected to bus master devices and slave devices. It is a bi-directional network, meaning that one device, a master, sends a request to a slave, and the slave responds to that request. The PROFIBUS DP (Decentralized Peripherals) is used to operate sensors and actuators via a centralized controller in production (factory) automation applications.

During cyclic communication, a maximum length of input and output data is defined as 244 bytes in one telegram.

In the Profibus DP network, a master device can communicate up to 125 slave devices at a time. Every slave device has its GSD file for operating read write operation with the master device.

During profibus communication, the size of the telegram depends on the length of the data field. The master device collects all input/ output data from individual slave device and transfer to a PLC (programmable Logic Controller) device for processing. The PLC device stores all data values in PLC registers. So in effective way, maximum data should be stored in minimum PLC registers.

Generally, user configures the GSD file as per PLC requirement. For example, if user wants to read a parameter “A” (size: 4 bytes) from the profibus DP slave device, then data should be read as per parameterization id which is configured in GSD file. But if user wants to read only 2 bytes of data A, or want to reduce the size of parameter by adding some multiplication factor, then there is not any configuration provision in the GSD file.

There is no utility available which could provide data configuration facility without change in the GSD file as well as in software of the slave device. So, it is very difficult to manage the different slave’s data in fix bandwidth at PLC registers. In cyclic DPV0 communication data comes in input buffer as per fix module selected in the GSD file.

Further, if customer want to change the scope of any parameter, for example if the customer want to use only lower two bytes instead of 4 byte or, want to change unit of any parameter (Watts (for example) to k Watts ) without change in the GSD file, then it is not possible in existing utilities.

Accordingly, there is a need to provide a method which meet customer requirement by optimizing input data length so that user can utilize data bandwidth of PLC device more effectively.

Object of the invention

An object of the present invention is to optimize input data length in a slave device of the PROFIBUS DP.

Another object of the present invention is changing any parameter without change in the GSD file of the PROFIBUS DP as well as firmware of any slave device.

Summary of the invention

Accordingly, the present invention provides a method for optimization of input and output data transfer during profibus cyclic communication in a networked computerized industrial process control systems. The method includes connecting a relay with a computer using a communication module, and selecting a parameter required by a PLC master device. Specifically, the PLC master device is capable of communicating with the relay. Further, the method includes selecting bit information required by the PLC master device. Specifically, the bit information is changed by any one of clubbing required information and discarding the useless bytes. Furthermore, the method includes configuring the relay as per data sequence and selection, wherein the relay is configured by using any one of adding multiplication factor in current value of the parameter and sending only useful bytes of the parameter in a PLC register. Thereafter, the method includes configuring the PLC registers as per memory map selection, configuring the PLC master device with previously used .gsd file, and reading/writing operation with maximum data utilization.

Brief description of the invention

The objectives and advantages of the present invention will become apparent from the following description read in accordance with the accompanying drawings wherein,

Figures 1 shows a block diagram of a system for optimization for input or output data transfer during profibus cyclic communication.

Detailed description of the invention

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment.

The present invention provides a system and method of optimization for input or output data transfer during profibus cyclic communication.

Referring now to figure 1, there is shown a system (100) for optimization for input or output data transfer during profibus cyclic communication. The system (100) includes a PLC (profibus master) (10), a relay (20), a configuration PC (30) and GSD file (40).

In another aspect, the present invention provides a method for optimization for input or output data transfer during profibus cyclic communication. The method includes connecting the relay with computer using any communication utility. In an embodiment, the communication utility is Modbus. However, the communication module may be support other protocol also.

Further, the method includes selecting the parameter which is required by PLC master. In an embodiment, the parameter may be selected from ID, Size (length of parameter), multiplication factor and the like.

Furthermore, the method includes selecting bit information which may be required by the PLC device.

Thereafter, the method includes configuring the relay as per data sequence and selection and configuring the PLC registers as per memory map selection.

Moreover, the method includes configuring the master device with previously used .gsd file. There is no need to change the GSD file. The user can start data reading/ writing operation with maximum data utilization.

The present invention is described now with the help of following examples.

Case-1: Suppose in GSD file following parameters are defined:

Parameter ID Name of Parameter Default size of parameter ( Byte)
1 Protection trip flags 1
2 Current in Amp 4
3 Voltage in Volt 4
4 Energy in watt 8

At PLC, 120 relays are connected as a slave device with one master device. Maximum PLC register size is 1080 Bytes. Then how will the PLC manage whole data base of all devices?

Problem: As per GSD file default size of whole module is: 1+4+4+8 = 17 Bytes
No of relays: 120
So PLC register size required: 17*120 = 2040 Bytes. So it’s not possible to manage whole data in current PLC register size.

Solution: Using configuration utility user can configure relays as following two schemes:

Scheme 1: (if measurement range (values) are large)
Parameter ID Name of Parameter size of parameter ( Byte) Multiplier factor
1 Protection trip flags 1 1
2 Current in Amp 2 1000
3 Voltage in Volt 2 1000
4 Energy in watt 4 1000

If measurement values are too large and user is unable to accumulate in two bytes of data then user can add a multiplication factor in current value.
E.g. if Energy = 68719476735 Wh
After multiplication, Energy = 68719476735/ 1000 = 68719476 kWh

Scheme 2: (if measurement range (values) is low)

Parameter ID Name of Parameter size of parameter ( Byte) Multiplier factor
1 Protection trip flags 1 1
2 Current in Amp 2 1
3 Voltage in Volt 2 1
4 Energy in watt 4 1

If real time values of measurement parameters are small enough which can accommodate in small register then scheme 2 will be used.
E.g.: Default size of current register is: 4 Bytes (allocated in relay) and maximum value of current will not exceed 2 bytes of data. In this case user can configure relay like: relay will send only first two bytes of four bytes of data. Because remaining two bytes are useless.

Case-2: Suppose in GSD file following parameters are defined:

Parameter ID Name of Parameter Default size of parameter ( Byte)
1 Protection trip flag0 1
2 Protection trip flag1 1
3 Protection trip flag2 1
4 Protection trip flag3 1
5 Current in Amp 2
6 Voltage in Volt 2
7 Energy in watt 4

Bit:7 Bit:6 Bit:5 Bit:4 Bit:3 Bit:2 Bit:1 Bit:0
Protection trip flag0 IOC_S1-N IOC_S1_Pb IOC_S1_Py IOC_S1_Pr IOC_S0-N IOC_S0_Pb IOC_S0_Py IOC_S0_Pr
Protection trip flag1 TOC_S1-N TOC_S1_Pb TOC_S1_Py TOC_S1_Pr TOC_S0-N TOC_S0_Pb TOC_S0_Py TOC_S0_Pr
Protection trip flag2 IOC_S3-N IOC_S3_Pb IOC_S3_Py IOC_S3_Pr IOC_S2-N IOC_S2_Pb IOC_S2_Py IOC_S2_Pr
Protection trip flag3 TOC_S3-N TOC_S3_Pb TOC_S3_Py TOC_S3_Pr TOC_S2-N TOC_S2_Pb TOC_S2_Py TOC_S2_Pr

At PLC, 108 relays are connected as a slave device with one master. Maximum PLC register size is 1080 Bytes. Then how will PLC manage whole data base of all devices?
Suppose As per customer need it is decided that we need only highlighted trip information in protection flags.

Problem: As per GSD file default size of whole module is: 1+1+1+1+2+2+4 = 12 Bytes
No of relays: 108
So PLC register size required: 12*108 = 1296 Bytes.
So again it’s not possible to manage whole data in current PLC register size.

Solution: In this case user can change the bit mapping as below table:

Bit:7 Bit:6 Bit:5 Bit:4 Bit:3 Bit:2 Bit:1 Bit:0
Protection trip flag0 TOC_S1_Pr TOC_S0-N TOC_S0_Py TOC_S0_Pr IOC_S1-N IOC_S1_Pb IOC_S0_Pb IOC_S0_Py
Protection trip flag1 TOC_S3-N TOC_S3_Pb TOC_S3_Py TOC_S3_Pr IOC_S2-N IOC_S2_Pb IOC_S2_Py IOC_S2_Pr
Protection trip flag2 IOC_S3-N IOC_S3_Pb IOC_S3_Py IOC_S3_Pr IOC_S1_Py IOC_S1_Pr IOC_S0-N IOC_S0_Pr
Protection trip flag3 TOC_S1-N TOC_S1_Pb TOC_S1_Py TOC_S0_Pb TOC_S2-N TOC_S2_Pb TOC_S2_Py TOC_S2_Pr

Using the above logic user can club required information in two bytes and discard other two bytes because those are useless from customer point of view.

So again as per GSD file default size of whole module is: 1+1+2+2+4 = 10 Bytes
No of relays: 108
So PLC register size required: 10*108 = 1080 Bytes.
So with this scheme now we could fulfill the need of customer.

In the case of protection relays a bulky protection, the trip data have to be transferred for the PLC device. Along with this bulky data some unused protection trip data have to be transferred at PLC device because of limitation of module which is selected on GSD end. One of more possibility, some additional protection bits may be required which is not defined in GSD file module definition.

Accordingly, the present invention provides the maximum flexibility for data configuration at customer end. The present invention is very effective when user wants to pass multiple parameters in a short input data length and when a single bit memory also can provide a big relaxation on PLC end.

Data configuration technique of the present invention provides user friendly environment for optimizing or reconfiguring any user parameter of protection relay remotely. This is a very efficient way to improve the utilization of PLC master. It’s an effective way to increase the efficiency of data communication with protection relay of PLC master up to 50-75%.

The method of the present invention identifies the customer requirement and provides the intelligence to a microcontroller so that the microcontroller can configure itself for relevant output during profibus communication.

The method includes developing user interface utility. Further, the method includes programming in relay microcontroller and developing user interface utility. The user interface utility can communicate with relay through any TCP/IP / serial or with any proprietary protocol. This utility will provide the data configure and arrangement facility before parameterization the relay. This one time approach after this relay will re configure all parameters itself without change in software or GSD file.

Further, the method includes programming in relay microcontroller. A mapping mechanism have to implement in relay microcontroller so that all parameters which are configured in the GSD file should be map with configured parameter configured threw user interface utility. All configuration settings should be save in nonvolatile memory in microcontroller.

The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment. Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter. The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention.