How to communicate with the instrument via USB to Serial converter using MAX?

[jhouwana]

Actually I want to send serial commands through this since the instrument that I am using does not respond to the GPIB standard (?IDN*).

My problem is I cannot connect with the instrument using MAX. I am a Vee Pro user and based on what I read, I need to use the NI-VISA to send serial cmmands to the instrument? Is that correct? Do I have to install NI-VISA drivers?

I badly needed your help. Thanks a lot! 😄

[smercurio_fc]

I don't understand why you believe you have to use serial commands just because the instrument doesn't respond to the GPIB *IDN? command. Lots of old instruments don't respond to that command but you can still program them over GPIB. Are you actually trying to talk to it over GPIB? What kind of GPIB card do you have? What is the instrument?

As far as serial is concerned, there are examples that ship with LabVIEW that show you how to do serial communication in LabVIEW. The important part is the termination character to use when sending a command and when receiving a command. 

In LabVIEW VISA is the recommended API to use, so yes, you should install NI-VISA.

[Dennis_Knutson]

Yes, you need to install NI-VISA. It's on your driver DVD or click on the support link at the top of the page.

Don't at all understand your comment about needing to use serial since the instrument does respond to *IDN?. You would use serial if the instrument does not have a GPIB interface or if you do not have a GPIB controller. The commands are irrelevant.

[jhouwana]

hello all,

thanks for the reply.

the only way to communicate with the instrument that I am referring to is through the USB to serial converter interface.  The equipment dont have any GPIB ports or connection. I just use the MAX to find the instrument. Thus, it displays the ASRL instrument.

[Dennis_Knutson]

MAX will not find any serial instrument. It will only find a com port. You have to know which com port your instrument is connected to. There are ways to do that but not in MAX. If MAX only displays one ASRL or Comx resource, then it would either be a built-in com port or your converter. If the resource goes away when you unplug the converter, you know you don't have a built-in port and you can proceed with whatever else you need to do.

[jhouwana]

thanks a lot Dennis..now I understand...so there's no way to do it using MAX.

I am now trying to do it using the Agilent I/O connection expert but this will now be off topic to ask questions here.

Thanks again! 🙂

[smercurio_fc]

You did not understand what Dennis said. This has nothing to do with MAX. The Agilent IO Expert will not give you a different result. There is NO established protocol for serial instruments that's equivalent to the GPIB protocol for finding instruments. Thus, the only thing that you will see is the COM port. You have to actively communicate with the instrument to find out if it's there.

[jhouwana]

hello again, yup there's no established GPIB protocol for that.

That's why I am using serial commands to communicate with the instrument via USB (from PC) to serial converter (to the instrument) interface.

Actually this has been successful using the VIsual Basic, and I would like to do it using the Vee pro and that's my problem.

just to clarify, the instrument that i am using is not the usual commercial instrument like Agilent, R&S, and other vendors. So there's no driver and others that i can search in the internet, the only information that i got from the maker of the instrument is the syntax or serial commands which are use to send instructions to the instrument and it is just a 4 liner serial commands,  and it is the same command that are use in the hyperterminal communcation.

[Dennis_Knutson]

You are not making any sense to me.

Stop making references to GPIB if you are not using it. If you want to use MAX to communicate, just right click on the VISA Resource in MAX. If you are using Vee, then I don't understand why you are using MAX, why MAX is even installed, and why you are even posting here. Vee is a product of Agilent. I don't understand the reasoning behind using that over LabVIEW but maybe you are one of the users that got it for free?

[jhouwana]

hello...

sorry for the confusion...yup i understand that it is easier to use the labview for this problem. 

our group just requires vee pro to use that's why i am asking.

anyway, thanks for patienly answering to my queries.