According to your question on using MSCOMM to send signal to serial prot, I would like to provide you the example as follows:
1. Please add reference in your project for Microsoft Comm Control 6.0. In order To use the MSComm control, you must install the related COM components of Microsoft Visual Basic 6.0 on the same computer that has Microsoft Visual Studio .NET installed.
'New a MSComm control
Dim MSComm1 As MSComm
MSComm1 = New MSComm
' Buffer to hold input string.
Dim Buffer AsString
' Use the COM1 serial port.
MSComm1.CommPort = 1
' 9600 baud, no parity, 8 data, and 1 stop bit.
MSComm1.Settings = "9600,N,8,1"
' Tell the control to read the whole buffer when Input is used.
MSComm1.InputLen = 0
' Open the serial port.
MSComm1.PortOpen = True
Console.WriteLine("Open the serial port.")
' Tell the control to make the Input property return text data.