How do I read and control an Omega CN7823/7523 using LabVIEW 8.5 and RS485?

[king10208]

Not quite yet.

Just using Omega's for awhile until I can get around to it.

[Avans]

Hi.Please find the simple VI below.This VI reads the process value and set point.Volodymyr.

[Jon_on_LV_8_5]

I would really like to see the VI you posted, but I can't open it.  I'm on LabView 8.5.1.  If it's possible for you to save it in an earlier version format and upload it, I would greatly appreciate it.

Thanks!

[Avans]

Please check the file attached.

It is a pretty simple VI to explain the way how it works.

Volodymyr

[ashish-singh]

Dan

I also have 7523 Omega controller and I found a simple Vi built from the Modbus library in NI.

I was wondering if i need a driver for this controller to talk to labview?

[Tim_O1]

You will need a driver for your 7523 Omega controller so LabVIEW can communicate with it.

NI does not provide drivers for third party hardware, but you might find one on Omega's web site.

Once you find a driver that works for your device these are the next steps you will need to take.

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P8THSA0&l=en-US

Tim O

[Avans]

There is no driver for this controller, but you can use MODBUS driver to send commands to the instrument.

Be advise that the real address of controller is 4700 (not 1000 as it described in manual)

[ashish-singh]

Thanks Tim and Avan,

for the driver, if I use a MB serial query and set up the right communication parameter, do I still need a driver?

Secondly, I found an existing VI for the similar controller? When I am running the VI, I am getting an exception  code 2 . Does this mean something is wrong with the address of the register?

[Tim_O1]

Hi Ashish,

Take a look at the document below, it may have everything you need to know and the FAQ has some good answers. I am not sure if your problem is the "address of the register" it would help if you post a screen shot of your error and your code.

Introduction to MODUS

https://www.ni.com/en/shop/labview/introduction-to-modbus-using-labview.html#section-2038101968

Tim O

[ashish-singh]

Tim,

somehow, the VI is able to read and write couple of registers in the controller.  

Some of the things that i changed included "mode to RTU" and using decimal for the Address of the register. OMEGA manual still reports hexadecimal representation for the address, and I dont know why?

Also, Omega is still saying the mode is ASCII. I tried and it didn't work. RTU works. I exactly dont know the difference between these two modes, but I believe it has to do with the use of data types for communication and so on.

I will keep you posted with the modification.