Ethernet Communication Labview

Ethernet communication Labview

Setting Up A Server

So a server is created on external system using labview. All the required VI’s are present in function palette under Data Communication->protocols->tcp\ip.

First client sends a signal to server to start the communication and the server replies with a data packet which in our case is a XML string. Therefore “TCP Listen.vi” is used which waits for an incoming signal. Input Output

Port:6008 Connection ID: Unique ID and is

used in subsequent blocks. Net address: String to IP. vi

present TCP\IP palette.

Remote Address: IP of the client(Robot).

As it is evident from the flowchart that after receiving the request from client data is sent to robot therefore we will use “TCP write.vi “ .

Input Output

Connection ID: From TCP listen .vi Connection ID:Used in subsequent VI’s Data In: Data to be written which is

contents of file “ExternalData.xml”

Bytes Written: No. Of bytes transferred to client.

After This robot replies with a XML string and “TCP Read.vi” is used for receiving the data packet.

Input Output

Connection ID: From TCP Write .vi Connection ID: Used in subsequent VI’s

Bytes to read: No. Of bytes to be read 340 in this case . Use hit an trial

method to figure out no. Of bytes.

Data Out: Received Data .

Three main parts covered are:

2. Joystick interface with labview. 3. Setting up a server in labview .

 It is the image of main VI

 Outer while loop runs continuously ,waiting for an incoming connection and after receiving the request the inner loop is executed.

 Contents of file ExternalData.xml are read using Read from text file.vi and is sent to robot using TCPwrite.vi.

 Robot sends a data packet and it is received using TCPread.vi.  To send new data errorout of TCPread.vi is used.It is a cluster of 3

elements and one of them is a Boolean. When there is no error its value is false .

 A case structure is used and it has two cases either false or true. Errorout of TCP read.vi is connected to its input after inversion using not gate.

Whenever server reads the data successfully it calls the structure and subvi is called.

 Instead of using the received data for current coordinates content of ExternalData.Xml is used which has the last sent coordinates using Read

from text file.vi(6)

Read from text file.vi Input Output File(use dialog):Path of

externaldata.xml on the hard drive

Text:Contents of the file

 After reading the data we use Matchpattern.vi(1) to get the positon of values of X,Y,Z in the file.

Match pattern.vi

Input Output

String: Connected to output of (6). Offset past match:Offset of the coordinates in the file.

Regular string:String just before the value of coordinates.

 Different match pattern.vi is used for each coordinate.

 Offset is used to extract the values of coordinates using String

subset.vi(2).

String subset.vi Input Output String: Contents of

externaldata.xml

Substring: Value of coordinate. Offset: Connected to match

pattern

Length: Length of string to be extracted.

 Coordinates from String subset is the form of string and is converted to an integer using Frac/Exp string to number vi(3).

 These coordinates are added to the increment value obtained from joystick.

 New coordinate values are converted to string using Number to

Number to fractional string VI

Input Output

Number: Input number F-Format string: Coordinates in form of string.

Width: Number of digits needed to represent the number .Value is 7 Precision: Number of digits after decimal point. Value is 2.

 Using Replace substring vi (4)the values of coordinates are updated in externaldata.xml.

Replace Substring vi

Input Output

String: content of ExternalData.xml Result string :complete string after replacing substring .

Substring: Connected to (5).

Offset: connected to match pattern vi.

Length: length of substring.

 Three replace substring vi’s are used , the output of first vi will be the input of second and output of second will be the input of 3RD and output of 3RD will be the final string which is written in file EXternalData.xml .

 After the increment is calculated by moving the joystick ,button 2 is pressed which terminates the while loop and data is written to externaldata.xml using write to text file VI(7).

Write to text file.vi

Input Output File(use dialog):Path of

externaldata.xml on the hard drive Text:Connected to output of 3RD

Replace substring vi.

 After the file is written, inner loop of main vi starts to execute and contents of updated externaldata.xml is sent to robot.

 This process continues and there is continuous exchange of XML strings between external pc and robot.

 All the string related VI’s are present in function palette under programming->string.

 VI’s related to text files are present in function palette under programming->File I\O.

 For any queries related to labview use Google or post the problem on official labview forum and someone will definitely reply to the query.