Sending pulses through the serial port

[thiagoxmec]

Hello everybody. I need to send pulses with frequency of 1 Hz, with time at a high level 5us (microseconds) for about 30 minutes at pin 3 of the serial port (Tx). Already built the circuit RS232 to TTL conversion. And the program I have done the basic routine of sending signal through the serial port and already noticed its perfect functioning. My problem is I can not send a 0 to the output. In the writing pad VISASERIAL WRITE the value I place is represented in ASCII and can not send a zero logic level at the output. Already consulted the table and the NUL code that represents bits 0 not out. I tried to use the VI BREAK but it does not satisfy my project because it keeps the low level by only 500ms and a certain delay occurs.

In short, HOW TO SEND A BIT ZERO BY EXIT VISA SERIAL WRITE IN ASCII?? Wish my output becomes zero for a few seconds.
Thank you guys. Attached follows my program.

[Dennis_Knutson]

Does it have to be the tx pin? You have control of the hardware handshake pins with a VISA property node. You can assert/deassert.

[thiagoxmec]

Hello friend. Need not necessarily be the Tx pin. I just need to control the frequency and pulse width at high level around 5us.
How can I implement the VISA property node?
Thanks

[Dennis_Knutson]

I'm assuming you are setting the pulse width with the external circuitry.

[ebalci]

I think the pulse width is set by the baud rate.

I also used that approach in the past.

Serial ports can be a good alternative to pulse generators.

Their stability and accuracy may be enough for some applications.

ASCII 0 is the null byte and it cannot be typed directly.

But I am sure there is an escape character or something.

I am not very fluent in LV so cannot help you directly.

Good luck

[ebalci]

If you also have LabWindows installed on your computer, there is a sample RS-232 application.

Its workspace name is serial.cws

You can send hex represented bytes from that application.

If you are just trying to test the environment, you can use such tools.

[ebalci]

About your ultimate goal, I think Dennis has a point.

Even if you send a 0x00 byte, you will always have start and stop bits.

Which means if you do not generate the 1Hz delay from your computer, you cannot have a 1 sec pause on the line and a 5 microsec pulse with the same baud rate settings.

Sotware timing is not so reliable. Are you OK with that?