Burkert Type 8056 User Manual
Page 80
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RS232_485_ETP_MODBUS_BU_REV02.doc
5.9.
EXAMPLE OF SOURCE CODE FOR VB .NET 2005 PROJECT
The code below is intended as an example of source code for return the process data from the flow
meter via Modbus protocol.
The example uses the serial port control present in the tool box of the Visual Basic Net 2005
For the hardware communication it is used a converter RS232 – RS485 connected to the RS232 serial
port of the pc and the RS485 port of the converter.
The control line used in the example for the control of the transmission data in the RS232-RS485
converter is the RTS line.
The example program is an executable application that run in a Windows XP operative system. For
this reason the commutation of the RTS line is not immediately reached because the Windows XP is
multithreading system and the application haven’t the direct control of the hardware.
In other words there isn’t a direct control of the UART of the mother board by the application.
For this reason there is possible to insert a delay time by the function A.delay in the
Menu «7-
Communication» of the
flow meter for compensate the retarder.
Public
Class
Form1
Public
Delegate
Sub
myDelegate()
Dim
afIntChkHigh(0
To
255)
As
Integer
Dim
afIntChkLow(0
To
255)
As
Integer
Dim
vfStrErrorString
As
String
Dim
vfStrCommand
As
String
Dim
vfStrCrc
As
String
Private
Sub
Form1_FormClosing(
ByVal
sender
As
Object
,
ByVal
e
As
System.Windows.Forms.FormClosingEventArgs)
Handles
Me
.FormClosing
End
End
Sub
Private
Sub
Form1_Load(
ByVal
sender
As
System.Object,
ByVal
e
As
System.EventArgs)
Handles
MyBase
.Load
Try
'load checksum
afIntChkHigh(0) = &H0
afIntChkHigh(1) = &HC1
afIntChkHigh(2) = &H81
afIntChkHigh(3) = &H40
afIntChkHigh(4) = &H1