B&B Electronics MODSCAN32 - Manual - Manual (Page 81)

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Visual Basic Example
An example Visual Basic project is included with the modbuss.ocx distribution zip file. This example,
(Demo1), consists of a single VBA form containing standard text controls along with the Modbus Data
Control and Modbus Port Configuration Control contained within modbuss.ocx.
Operation of the Demo1 example scans the IO_Points defined by the edit controls based on a 5 second
timer tick. The status text is updated each second to display error conditions which may appear between
polls, (i.e. time-outs, etc.). Text1, 2, & 3 are used to defined the control’s data defeinition properties, and
the update button allows a data value to be written to the device.
The properties defining the serial port connection and MODBUS slave device address are configured at
build time by modifying the property pages associated with the two modbuss controls.
Timer1 is configured to run each second and is responsible for displaying the current status of the control.
Private Sub Timer1_Timer()
Call show_status
End Sub
Public Sub show_status()
If (Modbuss1.Status = 0) Then
Label4.Caption = "OK"
ElseIf (Modbuss1.Status < 255) Then
Label4.Caption = "Slave Device Exception Response"
ElseIf (Modbuss1.Status = 263) Then
Label4.Caption = "Slave Device Timeout"
ElseIf (Modbuss1.Status < 300) Then
Label4.Caption = "modbus.dll failure"
ElseIf (Modbuss1.Status = 300) Then
Label4.Caption = "Uninitialized"
ElseIf (Modbuss1.Status = 301) Then
Label4.Caption = "OCX Failure"
ElseIf (Modbuss1.Status = 302) Then
Label4.Caption = "Modbus Msg Overrun"
ElseIf (Modbuss1.Status = 303) Then
Label4.Caption = "Invalid Data Length"
ElseIf (Modbuss1.Status = 304) Then
Label4.Caption = "Invalid Point Address"
ElseIf (Modbuss1.Status = 305) Then
Label4.Caption = "Invalid Serial Port"
ElseIf (Modbuss1.Status = 306) Then
Label4.Caption = "Invalid Node Address"
ElseIf (Modbuss1.Status = 307) Then
Label4.Caption = "Invalid Data Index"
ElseIf (Modbuss1.Status = 308) Then
Label4.Caption = "OCX Demo Time Expired"
End If
End Sub