Serial Flow Control

[jyang72211]

Hi all,

I have a serial comm flow control question.  I am trying to get a driver going.  The spec says the device is using RTS and DTR, but not DSR and CTS.  It also says that "DTR line high" for the communication protocol.  See pic attached for the spec.  It seems to me that the device can do both RTS/CTS and DTS/CTS.  My questions are:

1. Howcome the spec is saying that DSR and CTS are not used?  Is it because they are on the receiving end?

2. It is true that both RTS/CTS and DTS/CTS are available?  Can I just use either or then?  When would I choose one over the other?  If I do choose one, do I just choose it in my software, or do I have to adjust my hardware too? 

The device is a Radian RD-33.   

Thanks!

Yik

[Dennis_Knutson]

There is a serial tutorial here with an explanation of the different handshaking options.

Just because the lines exist on the connector, does not mean that the instrument is capable (i.e. programmed) of using them. There are instruments where you can select the type of handshaking but it is not at all rare where only one type is available. For a direct connection to a pc, RTS/DTR is probably the most common (most common to me, anyway) and that is what you have to select on the LabVIEW end. You will notice that RI is also not used. This and DSR/CTS are often used with modem connections. Rare these days and why implement something that will never get used?