10 port valve control

[RavensFan]

You are confusing two things.  Enabling the termination charactering and configuring it on the Serial Configure subVI deals with the termination character when you are reading from the serial port.  It tells a VISA Read to end the read once it sees the termination character.  It has absolutely nothing to do with enabling the automatic sending of a termination character if you doing a VISA Write.  That is a separate setting that you need to do with a different property node.  I have never found a reason to use the automatic send of a termination character when it is so easy to just include that character in the string you are sending with the VISA Write.

[Fbaird]

Thanks. I guess I was. I'm not overly familiar with serial communication.  I appreciate the explanation.

[Dennis_Knutson]

Since the VISA Configure Serial Port does nothing for appending a termination character, appending it is one way.

If the instrument is truly sending a termination character, it is not correct to use VISA Bytes at Serial Port or fixed delays.

[usman_o]

Hi mgouveia,

I just bought VICI 8-channel multiposition switching valve and need to do labview software to control the position of the valve based on timer. Can you help me on this matter as i am new to LabVIEW and my professor wants to get the data as soon as possible? What i do at this moment is manually press the button to switch the valve to next position. Your help is very much appreciated. thanks

[natasftw]

usman, that user's last post was in December of last year.  It's unlikely they are going to respond to you bumping an older thread.

If you are unable to get the code in this thread to work for you, you'd be better served by opening a new thread to ask your specific question.  Most people here tend to ignore zombie threads.

[Fbaird]

Just because I got emails about this quetions and there are something that I have managed to incorporate into my programs I will respond.  First question is did you buy the actuator that has the serial communication as a option?  There are a couple of different options when buying those valve actuators.  The base model uses TTL signals where there is one pin that needs to be pulled down to ground.  This can be done with any of the NI DO cards and a relay. 

If you do have the seial option then previously in this thread there is an example that I posted that will work to send commands to move the valve as well as query it for its status.  But if your actuator doesn't have the serial option then it won't do you much good.

[romulonch]

Good night. I'm trying to develop a control system in labview able to change continually the position of a vici valve with 8 ports. I'm using a daq to connect labview with the valve using the daq assistant present in the labview. I'm already able to send simples commands using a boolean control and changing one position at a time. The problem appears when I try to configurate the daq assistant in a way that these changes happen continually. I'm really stuck here.
I would like to know if someone already tried to implement this type of control and perhaps could help me out. I'm using digital outputs.Thank you.

[RavensFan]

I recommend starting a new message thread rather than adding to a 2 year old thread that only the subject title seems related to your question.

When you post that new thread, attach your VI.  You say you are stuck and need help, but there is no way we can help you when you don't tell us where you are stuck or show us how far you have gotten.

Be sure to read these links that were posted at the top of the LabVIEW forum.

New to the Discussion Forums? Find information on how to get started here. We also ask that you abide by the NI Discussion Forums User Guidelines.

[Fbaird]

I think the problem you are having is with the "continuous" mode of your DAQ assistant. Likely the issue is the speed at which your program is writting information to the DO channel.  The Vici actuator like most industrial equipment need clear slow commands that are at least 100ms long.  I say slow because for the compter you are running your program on 100ms is an eterinty.  That 100ms interval needs to be observed for both the true signal and the false signal.  When you configure your continuous mode you can set the frequency that it writes, but rather than using the continuous mode you can just use the on demand and then use the labVIEW program to change the value that you are writting to the DO channel.  Then you just write a program that would consist of a while loop with a 100ms wait, a shift register with a boolean wire, and a negate function.  The boolean would change values every 100ms, that could then be wired to your DAQ write function and as long as the program is running the valve would keep chaning positions. 

So that is how you could make that happen.  The real question is why would you want to have the valve continuously changing ports?  Usually you want to stay at one port for some period of time to collect a sample then change to the next port to collect another sample.  It sounds like you are trying to use the actuator as a stepper motor. to drive something other than a valve.  If that is the case I would highly recomend that you just get a stepper motor.

[fcoelhocunha]

Fbaird, thank you for the advice. I'll try to implement what you said. Answering your question, the process I'm working on requires that the valve changes its position from time to time, for example, the valve needs to go from one position to the next after one hour in a continuously way. I tought that with labview I could create a system able to control automatically these changes, using the daq assistante for example