serial communication mark space

[mfitzsimons]

I need to send Mark and Space characters using serial communications. I have not found a way to do this with LabVIEW. Anyone have any knowledge on this topic?

[alipio]

Hello
Is not clear what do you mean with mark and space characters.
If talking about communications, mark is a 1 and space is a 0. So, you can use your serial port to send mark and space in Async characters ( start and stop bits.).Say baudot, ascii, etc. using the Visa serial vis.
Cheers
Alipio

[Emilie S.]

Hi mfitzsimons:

If you are using a VISA write in LabVIEW be sure that the string you are sending into write buffer is in '\' Codes Display. From here you can type \s for a space character. I'm also confused about what you mean by mark. Can you please give me a little more information on this?

Thank you,

Emilie S.
Applications Engineer
National Instruments

[mfitzsimons]

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@mfitzsimons wrote:
I need to send Mark and Space characters using serial communications. I have not found a way to do this with LabVIEW. Anyone have any knowledge on this topic?

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I have found the answer to my own question. Using VISA Configure Serial Port you can set the parity to Mark or Space. Here is some information on mark and space:

Mark parity means that the parity bit is always set to the mark signal condition and likewise space parity always sends the parity bit in the space signal condition. Since these two parity options serve no useful purpose whatsoever, they are almost never used.

For example, when even parity is chosen, the parity bit is transmitted with a value of 0 if the number of preceding marks is an even number. For the binary value of 0110 0011 the parity bit would be 0. If even parity were in effect and the binary number 1101 0110 were sent, then the parity bit would be 1. Odd parity is just the opposite, and the parity bit is 0 when the number of mark bits in the preceding word is an odd number. Parity error checking is very rudimentary. While it will tell you if there is a single bit error in the character, it doesn't show which bit was received in error. Also, if an even number of bits are in error then the parity bit would not reflect any error at all.

Source: http://www.taltech.com/TALtech_web/resources/intro-sc.html