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Serial port question

I've got a very simple application involving a PC transmitting (only) to a display over RS232. In theory only two wires are required Tx and Gnd as the display can "keep up" with whatever data rate the PC can produce. I'm using a test program that has the following handshake options "None, XON/XOFF, Hardware etc". I'm assuming that if I select "none" then the test program won't use handshaking but what about the UART itself?

Does the UART in a PC need hardware handshake lines pulled to a particular state in order to transmit?

Reply to
CWatters
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the

using

No, in my experiance it will work with all the other lines floating.

Reply to
Mjolinor

the

using

The protocols (both hardware and software) that govern PC serial communications are *all* dictated by the software. The UARTs themselves are just reporters of electrical facts.

Norm

Reply to
Norm Dresner

no it does not. but it may need the DSR line pulled up ?. that is just a guess.

CWatters wrote:

Reply to
Jamie

------------ If you bit-bang the port IO itself, no, but if you use the BIOS, then yes, you'll need the DSR and CTS to be fooled because the BIOS will require it.

-Steve

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Reply to
R. Steve Walz

Thanks for all the replies. I finally figured out that the display I was driving needed a higher voltage power supply.

If anyone else needs a simple app to test a serial port device then I recommend "Serial Device Tester" by Hack Consulting at

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Reply to
CWatters

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