Help with Modbus and a CAL 3300 Temperature controller needed!!

[francoisbeulz]

Hi,

Thank you for your reply, today i've tried exactly the same code as yours ( I think ) but it doesn't work for me, I still have the same problem : when I put 0 as adress for the slave in my code, I never have any error messages, but nothing happens for the temperature controler, whatever the adress I set to him. When I put a number different from 0 for the slave adress in my code, I have always erros message. What happens when your program is working ? Is the temperature controler screen changing like he is in a kind of remote mode or you don't see any changes ? Do you think the problem is the connection with the USB-RS232 cable ? Would you mind try my program on your temperature controler to see if its works ?

Thanks for your help,

Francois

[Sundown]

Hey, Just quickly read over your post. Set the address to something other than 0 in the code and then remember that you need to also change the address in the device itself. Have you been making sure they match?

[francoisbeulz]

Yes now it's working the problem was the USB-RS232 cable, thank you very much for your help ! 

[francoisbeulz]

Hey it's me again, my program is working well but I have a problem : when I change the value of the ramp rate manually or with my program, it doesn't change anything and the temperature controler keeps heating the furnace the same way. Did you have the same problem ? Maybe i didn't see a detail in the manual but I have red it many times..

[dudujiayou89]

Hi Sundown,

Thank you very much for posting your VI!  I installed it, and it initally works really well as far as the reading function goes.  Once I use the program to write a new set point to the controller, however, the temperature that the program reads goes to zero (regardless of the actual temperature on the controller).  If click on the "start read" function again, it will display the current temperature for a second and then go back to zero.  Any idea what might be going on?

Thank you in advance!

[mdc5235]

Hi All, 

I wrote the following VI to communicate with the CAL 3300 based on the what I saw here on this forum.  I think the code looks good, but for some reason, I keep getting a timeout error.  Could someone please look over what I have and let me know if you see any problems.  Thank you!

When I press "OK" in the program, the two sides of the debug lights will flash on the device, but Labview will show an error, and the setpoint will not be changed.

Thanks for your help!

Mitch

[beccamir]

What error do you get? 

Can you post a screen shot?

[mdc5235]

Hi Becca,

Thanks for your help!  I've put the error messages I'm getting as well as probe values into the following word document.

-Mitch

[beccamir]

mdc5235,

It looks like you are using the Modbus API library and not the DSC module. Is this correct? Do you have access to the DSC module? This would make setting this up much easier. 

Please see more infotmation on the Modbus API and the DSC module here: http://www.ni.com/white-paper/7675/en/

If you are using the Modbus API I encourage you to look at the examples in the NI Example Finder by going to Help>> Find Examples. Then search for Modbus. 

[mdc5235]

Hi Becca,

I do have access to the DSC module, and as far as I know, I'm using the low-level modbus API as described in the documentation that you sent me.

-Mitch