serial port dts

[tomsch1]

ok i'm starting this problem in a new thread as it has evolved.
I am using the following vi to turn and led on/off. it works fine as long as i disconnect pin 4 on my serial cable.
the VB app the i use keeps the dtr at -11vdc. when i use use the vi pin 4 goes to about 6vdc at about 15khz,i have not looked at it with a scope but i am guessing its a square wave, the settings i'm using are 115,200,8,n,1 and no flow control.

my first question is why if i have flow control set to none why is the dtr pulsing?

second if as i suspect the dtr is pulsing how do i stop it and set the dtr to a known state in this vi.

additional info the op sys is windows XP and i'm using labview 7.

comment: why doesn't labview initialize the serial port like you
would under VB or any other language for that matter??

[Lorand]

Hi Tomsch1,

the normal VISA serial-com functions you use in your app don't use the controll-pins of the serialports.
If you need to work with DSR/DTR,... you will have to use a property-node on the VISA-Resource.

Right-click on the Control/Wire "VISA-Resource-Name", then create/properties/modem-line-settings/...
(I hope I took the right words because I use a german version).

You can write and read the properties.

Lorand