Serial communication

[vvk]

Hello,

I am using labview 6.1 Serial communication.vi example. When I short  pins 2 and 3 of DB9  -DB9 female female connector  I can write and read.
 But when i connect a DB9 to DB25 adapter. I cannot read back anything it just times out. (I have tried different adapters - so the problem is with serial communication). Any suggestions?

[Dennis_Knutson]

And are you shorting pins 2 & 3 at the end of the DB25?

[vvk]

    yes the interesting part is that it works fine in labview 7.1 on my laptop. But in the lab on the desktop which has 6.1 version it wont .

[vvk]

    yes the interesting part is that it works fine in labview 7.1 on my laptop. But in the lab on the desktop which has 6.1 version it wont .

[Dennis_Knutson]

That is weird. There should no reason why it work with a DB9 cable but not a DB9w/DB25 adaptor. You could have different versions of VISA on the two different computers but I don't see how that would make a difference. Is the DB9 to DB25 adaptor a long cable or just one of those short little widgets?

[vvk]

It 10ft long DB9 to DB25 adapter.

[Dennis_Knutson]

I'm wondering if it's just a problem with the cable length and different UARTs on the pc and laptop.

The other question I forgot to ask is whether you are using the old serial driver in your 6.0 application or whether you are using VISA. Version 7.1 only supports VISA so maybe there is a problem there.

[vvk]

That is a good point. In 6.1 the vi uses Serial Read sub vi where as in 7.1 it uses VISA read sub vi. Maybe there is something wrong with that Serial Read in 6.1.
Thank you for your help!!