B&B Electronics MODSCAN32 - Manual - Manual (Page 47)

47
Visual Basic Example
The example Visual Basic application included with the ModScan32 distribution files is a simple take-off
on the ModScan application itself. The Form creates four array points, (one each for inputs, coils, input
registers, and holding registers). A timer is used to read and update the data once per second. Edit controls
are used to define the addresses as shown below:
Code for the example follows:
Public m_svr As IModSca
Dim PollHandle(4) As Integer
‘Handle for each of the four array points
Dim status(4) As Integer ‘Status return value for each ReadValue request
Dim SlaveDevice As Integer ‘All points use same slave address
Dim StartAddress(4) As Long ‘starting address for each array
Dim Modbus_Id(4) As Long
‘ prefix for selected address
Dim Counter As Integer
Dim temp As Integer
Dim Modbus_Addr As Long
‘qualified 5-digit modbus address
Private Sub coiladdress_Change()
‘
‘ User has changed address for coil array
‘ recalculate 5-digit modbus address
‘ and ModifyPollRequest accordingly
‘
If (IsNumeric(coiladdress.Text)) Then
StartAddress(1) = coiladdress.Text
Modbus_Addr = Modbus_Id(1) + StartAddress(1)
status(1) = m_svr.ModifyPollRequest(PollHandle(1), SlaveDevice, Modbus_Addr, 10)
StatusMsg (status(1))
End If
End Sub
Private Sub Device_Change()
‘
‘ User has changed slave device
‘ Modify all four PollRequests
‘
If (IsNumeric(Device.Text)) Then
SlaveDevice = Device.Text
Modbus_Addr = Modbus_Id(0) + StartAddress(0)
temp = m_svr.ModifyPollRequest(PollHandle(0), SlaveDevice, Modbus_Addr, 10)
Modbus_Addr = Modbus_Id(1) + StartAddress(1)
temp = m_svr.ModifyPollRequest(PollHandle(1), SlaveDevice, Modbus_Addr, 10)
Modbus_Addr = Modbus_Id(2) + StartAddress(2)
temp = m_svr.ModifyPollRequest(PollHandle(2), SlaveDevice, Modbus_Addr, 10)