serial behaviour

[chyrus]

Hi,
I'm realizing a stand-alone application that uses the serial port to communicate with an external data logger. The biggest and more interesting problem founded up to now is the following: the serial behaviour. To test the stand alone application I've used the well-known operatives systems. Watching the bit streaming with an oscilloscope, I�d founded that some characteristics are different. For example, the voltage levels are not equal for every PC. This fact can be considered normal because of hardware differences, but how can I manage the fact that the application works well with a PC with a given OS (e.g. windows xp pro) and sometimes with a PC with win 2000 pro installed?
Have someone founded the same trouble?

[Chris_Rake]

These are likely two unrelated issues. The difference in voltage is common, and as long as the voltage is outside of the +/- 3V band (and within the +/- 25V band), perfectly acceptable.

The difference not working between XP and 2k is a little more concerning. Are you using a built-in COM port or an add-on port?

[chyrus]

Dear Chris,

I thank you for the quick reply. I have supposed that the voltage difference might have been normal. But about the serial kinds I didn't know. To be sharp, I understand the existence of hardware differences, but how can I discovery about these differences? In this case, for example, I'd bought a new PC to make the trials, where may find I the difference from a built-in COM port or an add-on port?

Thanks again 4 attention

Chyrus

[Chris_Rake]

This may be hard to find. If you're looking for the differences in transceivers you'll have to know how a given PC's motherboard implements RS-232. You might be able to get this info from the MB manufacturer, or you might get lucky and be able to figure it out by looking at the motherboard. However this may be a challenge as MB vendors use a lot of intergrated peripherals these days.