topic Re: How to change "ASRL2:... " to "COM1"? in LabVIEW

How to change "ASRL2:... " to "COM1"?

hugoliang — Wed, 13 Dec 2006 00:32:46 GMT

Dear All,

I have used com port in my vi. And When I run it in edit mode, the selection of com displays "COM1,COM2,LTP1".

But when I build it, and run it in another PC, it displays "ASRL2:...".

How can I modify my vi to make it display COM1... in another PC?

And If I only want to display all serial port such as COM1,COM2... ,and not display LTP1.

I don't know how to modify it. Please give me some suggestion.

Thank you very much!

Hugo

Re: How to change "ASRL2:... " to "COM1"?

RayFarmer — Wed, 13 Dec 2006 07:18:09 GMT

Hi,

You need to assign the Alias of COM1 to "ASRL2..." and you can do this in MAX.

Regards

Ray Farmer

Re: How to change "ASRL2:... " to "COM1"?

hugoliang — Wed, 13 Dec 2006 12:14:34 GMT

Thank you for your reply.

I want to run my program in a PC which has not installed LabVIEW. Surely MAX is also not installed in that PC.

So, Is there any other good method?

Thank you.

Hugo

Re: How to change "ASRL2:... " to "COM1"?

pincpanter — Wed, 13 Dec 2006 12:31:40 GMT

MAX settings are written to c:\VXIPNP\WinNT\NIVisa\visaconf.ini. You can make changes to this file manually, taking the corresponding file on the development PC as an example.
See also http://digital.ni.com/public.nsf/websearch/BF528312C9A5423A862565BC00731EC0?OpenDocument

Re: How to change "ASRL2:... " to "COM1"?

hugoliang — Thu, 14 Dec 2006 12:58:15 GMT

Thank you.

I have checked the file "visaconf.ini", it is different in my PC and in another PC that I have installed my program.

But how can I to build my vi to let it copy "visaconf.ini" from my PC to the destination PC automatically?

And how to delete the LPT port in order to display serial port only?

Thanks.

Hugo

Re: How to change "ASRL2:... " to "COM1"?

RayFarmer — Thu, 14 Dec 2006 13:18:59 GMT

Hi,

Its a text file, use a text editor such as notepad.

regards

Ray Farmer

Re: How to change "ASRL2:... " to "COM1"?

Nallez — Thu, 14 Dec 2006 13:57:50 GMT

Nothing anymore.

Message Edited by Nallez on 12-14-2006 07:58 AM

Re: How to change "ASRL2:... " to "COM1"?

Marc_A — Thu, 14 Dec 2006 14:14:25 GMT

Here's a VI I use to do what you want. I don't even worry about aliases in MAX, I do them myself. This VI will only find serial ports, though. You would have to change it to find parallel ports or GPIB ports. It returns an array of clusters, each containing an alias and the actual VISA address. This way you can display the alias to the user and pass the actual address around in the program and you won't have to worry if aliases are set in MAX.

Message Edited by Marc A on 12-14-2006 09:14 AM

Re: How to change "ASRL2:... " to "COM1"?

RayFarmer — Thu, 14 Dec 2006 14:26:27 GMT

Hi Marc A,

Cant see you VI at present (no LabVIEW available on PC) but I guess you are using the ASRL resource name to send to the VISA open and using the Alias in some control the user can select?

Regards

Ray Farmer

Re: How to change "ASRL2:... " to "COM1"?

Marc_A — Thu, 14 Dec 2006 14:32:25 GMT

Exactly. Then the user sees what you want them to, and you don't have to worry about VISA aliases in MAX.

Message Edited by Marc A on 12-14-2006 09:32 AM

Re: How to change "ASRL2:... " to "COM1"?

Marc_A — Thu, 14 Dec 2006 15:23:02 GMT

Oh, I just remembered one other thing. That cluster that my VI outputs can be wired directly to the Strings and Values[] property of a combo box. Then you really dont have to worry about anything. The user sees the string and when you read the combo box, you get the value which is the VISA address. That's why I made it like that.

Re: How to change "ASRL2:... " to "COM1"?

hugoliang — Fri, 15 Dec 2006 00:34:38 GMT

Hi,

Thank you for your reply.

I am sorry to say that I haven't understood exactly and your vi attached can't be opened for my version is 7.1.

Could you help me to convert it?

Thank you.

Re: How to change "ASRL2:... " to "COM1"?

Marc_A — Fri, 15 Dec 2006 14:31:03 GMT

Ok, I've saved it for 7.1

Open the VI, you will see that the combo box has no values. Now run the VI. All COM ports on your computer will be detected and added to the combo box.

Now, what you see in the box is COM1, COM2, etc. However, the actual values of the combo box are ASRL1::INSTR, ASRL2::INSTR, etc. I added an indicator so you can see the value of the first element after it has been set.

Using this, you can connect the combo box output to any of the VISA VI's and it will receive the actual VISA address of the COM port without you having to set up an alias in MAX.

Re: How to change "ASRL2:... " to "COM1"?

hugoliang — Sat, 16 Dec 2006 01:20:06 GMT

Oh,Thank you very much.

I have understood it exactly after read your example.

Thank you very much.

Hugo

Re: How to change "ASRL2:... " to "COM1"?

GabrielaK — Thu, 22 Nov 2007 10:53:02 GMT

Hi,
even if this thread is rather old I hope that somebody can help me with this. I have a similiar problem like Hugo. In my program, I expect COM 1 to be ASRL1::INSTR etc. This worked fine by now for all COM ports on my machine, including a NI PCMCIA card offering 2 serial ports which were named COM 7 and 8, ASRL7::INSTR and ASRL8::INSTR respectively.

Now, I installed an USB ISDN adapter on this computer, and after that my NI PCMCIA card did not work anymore in LabVIEW. The COM ports assigned to this card are still COM 7 and 8. But, the VISA resource name assignments now are ASRL16 and 17, because MAX assigned ASRL7 up to 10 for the ISDN adapter!
So I thought, ok - I will propably have to find out programmatically which ASRL names are available on the machine and what are the aliases. Running Marcs "VISA Aliases Example.vi" I see that LabVIEW returns ASRL1 up to ASRL 8, but not 16 and 17. So I have no chance to see programmatically that the ASRL assignment has changed for the RS-232 PCMCIA card!

I was able to solve the problem by manually modifying the visaconf.ini file and set the ASRL assignments back to how they were before. But this is no solution, as I cannot expect our customers to do that in case that they run into the same trouble. So I hope somebody can help me with this.
Best regards,
Gabs

Re: How to change "ASRL2:... " to "COM1"?

pincpanter — Thu, 22 Nov 2007 13:37:45 GMT

Hi Gabs,
I sometimes have the same problem; this frequently happens when you add/remove serial ports, either multiserial PCI cards, USB adapters, even Bluetooth or Ethernet virtual ports.
Unfortunately, I have no solution for this problem, although the VISA Interface Description property may help (sometimes it contains the OS name, but it's not guaranteed).
I cannot understand why VISA doesn't return the OS resource name through a dedicated property (maybe this can become or more likely was already submitted as a product enhancement suggestion). The funny thing is that visaconf.ini seems to contain the right OS name, under the SystemName# key:

Name22 = "ASRL23::INSTR"
Enabled22 = 1
Static22 = 0
SystemName22 = "COM23"
etc.

One possibility would be to directly read this key, but this doesn't really make much sense; the location of the ini file may change - and it actually changed in the past.
It seems really stupid to compel the customer to make additional steps whenever the system configuration changes, as it's evident that VISA drivers MUST know which ASRL resource is associated to which COM port.

Re: How to change "ASRL2:... " to "COM1"?

GabrielaK — Thu, 22 Nov 2007 13:49:21 GMT

Hi Paolo, hi all,
hmm, so I am not the only one who struggles with this problem. Is there anybody out there who has a solution for it? Otherwise, how is a VISA based application using COM port controls supposed to work after adding other ports if these are confusing the COM<-->ASRL assignment?
Best regards,
Gabs

Re: How to change "ASRL2:... " to "COM1"?

Dennis_Knutson — Fri, 23 Nov 2007 04:10:47 GMT

I think that the com names and actual VISA resource names can be different is a very nice feature. The 'comx' names in VISA are just an alias. They can be anything you want. I usually name them to match the instrument I am connected to. Another nice thing is that if a program is using Com1 and the physical port dies (it's happened on several occasions for me), the old alias can be renamed (i.e. 'ComDead') and an existing or new USB-RS232 port can be called Com1. The program is back up and running in minutes.

If you want to use canonical names instead of aliases, you can set the VISA Resource Name to only display that and if you want to get the actual port from the alias, you can use the VISA property called Resource Name.

Re: How to change "ASRL2:... " to "COM1"?

GabrielaK — Fri, 23 Nov 2007 08:06:48 GMT

Hi Dennis,
I partly agree with you. Just partly, because in my opinion it doesn't make sense to confuse the ASRL settings for existing ports when new ports are installed (in that special case it was even just an ISDN modem which was added).
In my driver, I do not want to use the aliases as VISA Resource Name inputs as this made trouble when switching to another machine, and is not compatible with other operating systems. Also, I consider the fact that the VISA Find Ressource VI does not show the real settings a bug. MAX shows that COM7 is ASRL16::INSTR, but VISA Find Ressource VI returns ASRL1 to 9 only.
Anyway, your suggestion using the VISA property Resource Name solves my problem. It is not that easy, as my selection box offers COM1...x to the user (it is not a program but a driver VI, so I cannot run it in advance to find out which aliases are available on this machine) and I have to typecast the resulting string COMx to a VISA resource to be able to use the property. But then it works and I get ASRL16 for COM7. Thanks a lot.
Still, I think this behavior and particulary the fact that VISA Find Ressource does not return the correct ASRL settings is not user friendly.
Best regards,
Gabs

Message Edited by Gabs on 11-23-2007 09:06 AM

Re: How to change "ASRL2:... " to "COM1"?

Dennis_Knutson — Fri, 23 Nov 2007 15:02:32 GMT

On the system I'm using right now, VISA find Resource returns ASRL1, ASRL2, and ASRL10. What are you using for an expression and what are you using for the search mode? And why are you typecasting the strings? You can wire a 'Com1' string or ASRL1 string directly.