Omega CN7500 communication (ASCII protocol)

[Dennis_Knutson]

Do you actually have NI-VISA installed? What version?

MAX will never recognize the actual instrument, just the port.

I don't understand why you can't find the modbus driver. You can install an older LabVIEW version. You don't need it to detect the com port.

[dextor1]

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@Dennis_Knutson wrote:
Do you actually have NI-VISA installed? What version?

MAX will never recognize the actual instrument, just the port.

I don't understand why you can't find the modbus driver. You can install an older LabVIEW version. You don't need it to detect the com port.

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Hey Dennis,

Yes, I installed NI-VISA5.3,

When I reinstalled NI softwares, now I am able to see COM options which is related to my CN7500. However, the example VI does not give me correct readings, always shows 0.

Do I have to have modbus installed? And do I have to install an older Labview version to get the job done? It seems CWT (Message #13 in this post) can run it properly with Labview 2012, not sure if modbus is installed in this case.

Anyway, thanks so much. I am expecting your inputs.

[CWT]

Hi dextor1,

You do not need to install modbus to get this to work.  Do you have the CN7500 device plugged directly into the COM1 port of your pc or are you using an RS232 to USB converter?  Are you using an RS485 to RS232 converter before connecting to your pc?  I know these are basic questions, but it is a starting point for troubleshooting your issues.

Cory

[dextor1]

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@CWT wrote:

Hi dextor1,

You do not need to install modbus to get this to work.  Do you have the CN7500 device plugged directly into the COM1 port of your pc or are you using an RS232 to USB converter?  Are you using an RS485 to RS232 converter before connecting to your pc?  I know these are basic questions, but it is a starting point for troubleshooting your issues.

Cory

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Thanks Cory,

I use a RS232 to USB Plus a RS485 to RS232 to connect my pc and CN7500. The whole setup is assigned to COM4, however when i select COM4 in the Example.vi, it reads 0 numbers always.

I am not sure how to set the CN7500 having a 'flow control' to be 'NONE', can this be a big problem? I am tring to get a more detailed manual of CN7500 to see how to configure this setting. Not sure what's next...

[CWT]

Many times with serial instruments the port configuration will play a major role in getting it to talk to the software properly.  I would definitely start with making sure the serial configuration settings match what is on the CN7500 exactly.  The next thing to consider is making sure the controller number matches what is on the program.  I have the address defaulted to 01.  Also, the "Controller Number" text box should be configured as '\' Codes Display when you right click on the control.  If for some reason it is Normal Display, you will need to change that as well.

Cory

[CWT]

Hi dextor1,

I am attaching a user manual for the CN7500.  If you go to page 22, it lists a function called "CoSH" (2nd one down from top) that you must set to "On" in order to allow for communications via RS485.  Please check your controller to make sure this setting is correct.

Cory

[dextor1]

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@CWT wrote:

Hi dextor1,

I am attaching a user manual for the CN7500.  If you go to page 22, it lists a function called "CoSH" (2nd one down from top) that you must set to "On" in order to allow for communications via RS485.  Please check your controller to make sure this setting is correct.

Cory

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Hi Cory,

Yes, I have done this. You know, my trouble actually originates from the harware, when I switch to another usb-rs232 (also cheaper), everything runs well right now. No modbus, just stick with LV2012.

This is my first time using LV in my lab, there is a lot of fun. I may have further questions about the software, but I hope not.............

Thank you guys soooooooooooo much!!!!!

Cheers. 

[prad999]

Hello can you please attach the same file for  labview 8.5 version. i tried to save it in previous version but every time it shows error.

i shall be highly thankful to you if you could please convert the same file (Omega CN7500 v8.6.zip ‏429 KB) compatible to labview 8.5 version.

thanks