Question

Is it possible to raise/lower and read individual serial port lines from a C#/.NET application?

Like:

serialPort.Raise(DTR);
serialPort.Drop(CTS);
bool ctrStatus = serialPort.Read(DTR);

It doesn’t seem to be possible from the SerialPort class.

Answer 1

The pins you can control, you do via reading and writing properties.

i.e.

if (serialPort.DsrHolding)

note that the ability to set pins interacts with hardware handshaking if you have that configured.

For more control than that, you’ll need to access the Win32 API directly (for example using p/invoke or C++/CLI). The EscapeCommFunction gives direct control over the control outputs and GetCommModemStatus queries the control inputs.