how to send RTS, DTR

[Nok]

I try to send control command to my device over Serial RS232c. Before I install Labview 7 ,I tested communication with Hyperterminal, it works. But after I install Labview program and use Serial write example, it doesn't work. And after that hyperterminal waiting for reading and can't send control command to the device. So, I think maybe the problem come from the pin RTS,DTR didn't set and the command can't be send out to the device.

Somebody has an idea to deal with it, pls reply me.
Thank a lot.

[Chris_Rake]

RTS or DTR controls data transmission if flow control is turned on. Do you want flow control on?

[Nok]

Do u have any idea why when I send some command to the device, it doesn't work ??

[Chris_Rake]

For example, if flow control is turned on and CTS is deasserted (RTS from the device) then data will not transmit. If you don't need flow control, make sure it is disabled, and/or verify that the flow control signals are properly wired.

[Nok]

I try to send the command without Flow control but it still doesn't work. And I try with loop test by short pin 2 and 3, it works !!! the character sended appear on Read string.

why I cannot communicate with other device (both labview and Hyperterminal). But before I install Labview I test communication with Hyperterminal, it works.!!

What should be the problem ?

Thanks for ur help.

[Chris_Rake]

Hmmm - it really sounds like a configuration issue. You've double checked the baud rate, parity bit, and stop bit settings?

[Nok]

Yes..I set everything the same as the first time that it's work. Right now, I don't know what is the problem. (from Labview program or others)

[Chris_Rake]

In this case I would strongly recommend that you get hyperterm communication working first.

[Nok]

Hi. Chris.. thanks for ur help.
Right now Hyperterminal works but my program still doesn't work..

Could u see my code that it has sth wrong ?

Thanks a lot

[Chris_Rake]

I looked at your program and was able to communicate at 9600, 8, N, 1 with no flow control between the application and a hyperterm session. This is a very simple program and should work as long as you have the right settings and the right commands. I've attached my NI Spy record for you to compare.