RTS signal on a uart

I understand that the RTS signal on a uart is an active low output which notifies the other device when it can receive data by driving the pin low.

I have an FTDI cable connected to my computer and I'm driving the RTS line using the ftdi D2XX library. The functions to set and clear the RTS signals are here:

Set_RTS

Clr_RTS

By default the signal is low 0v, does this mean that I have to drive it high and then drive it low?

When I call Clr_RTS the signal goes high .155v. I thought it should go high when I call set_RTS()?

Thanks

By default the signal is low 0v, does this mean that I have to drive it high and then drive it low?

You don't have to "pulse" it.

I don't think it should be grounded (on the actual RS-232 line) because the actual RS-232 signals go negative & positive.

It can get tricky because both ends of the connection (and the baud rate & stop bits, etc.) need to "agree" and there are just lots of different configurations & options. And, the ends need to wired-opposite (so TX connects to RX, etc.), or you have to use a null modem cable/adapter to reverse the connections.

I'm looking at a schematic for something we have at work with two RS-232 ports. One of the ports has CTS & DTR connected together and pulled-up to 5V through a 3.3K resistor. On this particular port the cable plugged-in only has 3 wires so obviously the handshaking is not being used.

The other port has CTS and RTS connected together (with no pull-up or pull-down). I can't tell how many wires are used on this one.