about using external clock to control the timed sequence

[dragondriver]

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@Craig_ wrote:

It's still going to have to wait to get CPU time from the OS, so using that source won't improve the jitter.

You really need a Real-Time system for this application so that you can get bounded jitter and determinism! 

Check out this white paper:

What is a Real-Time Operating System (RTOS)? http://www.ni.com/white-paper/3938/en/

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Thanks for the information. I understand that it might not perfect, I just want to try if it will be a bit stable or not. I am reading the white paper in your link. It is quite confusing if the real-time property is due to the OS or hardware (PTX) or both? Since it is not possible for us to upgrade the PCI card to PXI one, I wonder if it helps if we change the OS to the real time OS and still using the PCI one. Honestly speaking, real-tim OS is really new to me. I use some linux distribution before and someone told me that linux is real-time? I don't know if there is any free distribution of linux support real-time task. Any think I am concerning is it seems that most of the module from labview support windows only. I wonder how much I can port my code into the linux without modifying too much.

p.s. I have two systems developed in Labwindows and in Labview 2013 (and MathScripts). I know that Labwindows definfitely not supported the linux platform. I wonder if I can use MathScripts or not.

[Craig_]

The Real-Time behavior is attributed to the OS's scheduler. Windows does not allow high priority processes guaranteed access to CPU resources, where as a Real-Time system does allow this.

You can use Mathscript Nodes on RT Targets!

Real-Time supports a number of different systems:

• PXI Real-Time: http://sine.ni.com/nips/cds/view/p/lang/en/nid/11154
• cRIO Real-Time: http://www.ni.com/compactrio/
• Real-Time Desktops: 
• Converting a Desktop PC to a LabVIEW Real-Time Target: http://www.ni.com/white-paper/2733/en/
• How do I Create a Desktop Real-Time System? http://digital.ni.com/public.nsf/allkb/398C100729B9CF438625790A0051DC1D
• NI LabVIEW Real-Time Deployment License for Desktop PCs: http://sine.ni.com/nips/cds/view/p/lang/en/nid/13751

You should not need to modify your code much to run on these platforms as LabVIEW provides a consistent platform to run code on any of the systems.

[dragondriver]

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@Craig_ wrote:

The Real-Time behavior is attributed to the OS's scheduler. Windows does not allow high priority processes guaranteed access to CPU resources, where as a Real-Time system does allow this.

You can use Mathscript Nodes on RT Targets!

Real-Time supports a number of different systems:

• PXI Real-Time: http://sine.ni.com/nips/cds/view/p/lang/en/nid/11154
• cRIO Real-Time: http://www.ni.com/compactrio/
• Real-Time Desktops: 
• Converting a Desktop PC to a LabVIEW Real-Time Target: http://www.ni.com/white-paper/2733/en/
• How do I Create a Desktop Real-Time System? http://digital.ni.com/public.nsf/allkb/398C100729B9CF438625790A0051DC1D
• NI LabVIEW Real-Time Deployment License for Desktop PCs: http://sine.ni.com/nips/cds/view/p/lang/en/nid/13751

You should not need to modify your code much to run on these platforms as LabVIEW provides a consistent platform to run code on any of the systems.

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Thanks. I read all those articles and I think to accomplish the target, it need either the real-time hardware or software real-time module. Currently, I don't think we could afford that.

What I am asking before is: could I setup some real-time OS (some free linux) and install labview in that linux so it supports most of the real-time functions.

[Craig_]

Unfortunately no, you will need to use the LabVIEW Real-Time module paired with a target running Real-Time to take advantage of the functions.

[dragondriver]

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@Craig_ wrote:

Unfortunately no, you will need to use the LabVIEW Real-Time module paired with a target running Real-Time to take advantage of the functions.

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Thanks for your reply. I just find that the license I was offered including the LabVIEW Real-Time Module (http://sine.ni.com/nips/cds/view/p/lang/en/nid/209855). But I wonder if this one supporting transferring the PC into a real-time system. Or if this module the same as NI LabVIEW Real-Time Deployment License for Desktop PCs so I can convert the PC into a real-tme system? Thanks.

[Craig_]

The Real-Time Module gives you a license to use the development software on a PC (the LabVIEW environment).

The deployment license allows you to put the Real-Time software on a target PC as an operating system, this cost is also factored in to every PXI RT system that we offer.

NI LabVIEW Real-Time Deployment License for Desktop PCs: http://sine.ni.com/nips/cds/view/p/lang/en/nid/13751

The option on that page titled "LabVIEW Real-Time ETS Deployment License Bundle for Standard PC's" with part number "779751-03" comes with a valid network card too!

[dragondriver]

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@Craig_ wrote:

The Real-Time Module gives you a license to use the development software on a PC (the LabVIEW environment).

The deployment license allows you to put the Real-Time software on a target PC as an operating system, this cost is also factored in to every PXI RT system that we offer.

NI LabVIEW Real-Time Deployment License for Desktop PCs: http://sine.ni.com/nips/cds/view/p/lang/en/nid/13751

The option on that page titled "LabVIEW Real-Time ETS Deployment License Bundle for Standard PC's" with part number "779751-03" comes with a valid network card too!

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So I only have the license to use the development software but I still need another license to deloy it to the target computer.

[Craig_]

The target's license is for the Real-Time PharLap operating system that is put onto it.

Deploying itself is more related to the host's software and the action of putting an application onto the targets.

But, disregarding the semantics, yes you are correct!