serial comms

[Veeru]

Hi

I have some doubt in serial comms, I am trying to send some data at 38400bps and read it back. It reads back as 0. But when i send at very low baud rate(for example: 110bps)it reads the right values. Is this problem because of hardware capability or something else?. Pls give some guidance.

I tried to communicate between 2 PC's via hyperterminal at 38400bps, it works fine.

Thanks

[aeastet]

You will have to know the capability of the hardware that you are talking to. Serial COM is very trick and needs to be done in a very spacific way. You  will need to pull up the specification sheet on the hardware that you are communicating with and find the limit of seep for that device.

[James_W]

Hi Veeru, 

1) have you set up your serial port correctly in LabVIEW?

2) do you have a big enough buffer (see 1)

3) do you have a timing issue

4) can you post your code - no one can diagnose problems easily without looking at code.

James

[Veeru]

Thanks All

At the moment i just tried to send data to PC and read it back.

I used the example program, "Basic Serial Write and Read"

Thanks

[LV_Pro]

Can you post your code, or an image (.png or .jpg, NOT .bmp). There are a number of ways to read serial data, some better than others, some that are much more time sensitive, meaning that they might work at low baud rate and not at higher.

[tbob]

What kind of cable are you using to connect the two devices?  Success at lower speeds but not at higher ones could be due to bad cabling, no shielding, crosstalk, etc.

[Veeru]

Thanks

Using the normal RS232 cable

[Coq_Rouge]

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Veeru wrote:

Thanks

Using the normal RS232 cable

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It is no such thing as a normal RS232 cable. The cable you have used for RS232 communication so far is a NULL-moden cable. It will work fine for communication between 2 computers. But that is no guaranty that this is the correct cable for instrument. Even if the cable connector fit. The de facto standard then it comes to RS232 cabling is NO standard at all

A reminder regarding RS232 Then in doubt never ever assume