RS-232 transmission for 'Labview' like programs

[jojos]

Hello. I would like your opinion about the project i am working on. I have finished the most of it and the only thing left is the transmission of some 16 bit data over RS232. I have to build such code that programs, like Labview, can receive that. So i am thinking sending first the '$' ,next x where x would be the marking of the variable i am sending e.g. $1 would be the litres variable, $12 would be some other variable e.t.c.
So if i am sending first the $ sequence and then with a printf sending the 16 bit data, would be OK or not?

My main concern is that if the program e.g. labview can understand this for example, Oh PIC is sending $1 ,so its the litres variable, so after $1 it follows a 16 bit variable (or 2 8 bit numbers to be more accurate because when i use printf and sending a 16bit number i can see on the oscilloscope that RS232 transmits 2 8bit numbers of course ). Is Labview capable of receiving 2 8 bit numbers and make them one 16 bit number or do i have to split my 16bit variable with the make8 instruction an send separate two 8 bit numbers e.g. $1 for the high part of the 16bit variable and $2 for the low part of the 16bit variable?

Thank you. I hope i haven't confuse you a lot

[Neutone]

[jojos]

This is the thing that i don't know what program will every the customer will use. So that is the reason i want to create such a code that every program like labview will understand. Also i left behind the idea of using printf instruction as it transfers also, besides, the real data, and data contain formatting values.
So i am splitting my 16bit variables and i am loading in the TXREG. Of course before every 8 bit variable i transfer the $x sequence. So i think i will include in the manual of the application information about the variables transfered through RS232 and for the string of recognition that is coming before any variable.

e.g.

$1 high byte of variable "litres", $2 low byte of variable "litres"

[Zer0flag]

Why don't you just send the numbers in plain text then? This way even a human will understand them. You can separate the numbers using CR or LF. As far as I know Labview should be able to recognize these automatically and extract the numbers without problems. Look for "Serial" and "VISA".

[jojos]

Zer0flag can you explain this more if you can? You mean i just have to send the variables through TXREG ,not with printf that adds formatting data, and in the end of each variable to send the 'LF' byte.My $x sequence is it necessary or not in this occasion?Could you give an example?Thank you

[Zer0flag]

I think you can use printf, why not? As I am also new to LabView I have just seen some examples and think this is the right way to do it.
Google for: visa serial labview

[jojos]

Another thing i wanted to ask is this.Lets say variable x=10 and i want to sent this value through Serial. If HyperTerminal recieve this data it will give a Line feed instruction ,cause 10 is the LF 'new line feed'. My question is this if i transmit x variable to Labview do i have to convert it in ASCII code or the labview will 'understand' that i am sending a variable with value of 10 and not a LF instruction?

[jma_1]

Greetings jojos,

Labview does a lot behind the scenes, but it is still just a programming language. A normal serial routine would determine the available bytes and then read them one at a time. If you have logic in the software to look for the LF no problem. If you read the LF and add it to a buffer, no problem. The LF is very distinct and can be searched for or removed if necessary.

The examples in Labview are numerous and very good. Most things from serial communication, event structures, state machines, data acquisition, FFT, etc. are covered.

I like Zer0flag's suggestion of sending ASCII text. If you send text, debugging any data sent is simple and intuitive.

Cheers,
JMA

[Steve H]

Here is a link to a project I did several years ago - All the code is available for download. It works with any programming language that can support a) serial or b) Microsoft ActiveX controls (which LabView and VEE can).

geocities.com/hagtronics/pic_das/index.html

HTH - Steve Hageman