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

[Sundown]

Hey! Just wondering how that worked out for you?

[erknoebe]

I tried to create something simple from the code you sent. It still looks like the code I wrote to start with. Was wondering if you have a RS 232 board included with your CAL 3300 or an RS 485. I have a RS 485 in mine so the wiring connections may need to be changed.

[erknoebe]

It is now working. I will follow up with a post tomorrow.

[erknoebe]

I downloaded the Modbus Library and was able to get the program working. I then went back and checked the Modbus functions in LabVIEW 2014 once I knew what I was doing and they worked also. The program had four errors that were solved by a couple of people. Three errors were solved by smithd. The default settings of the CAL 3300 is address 0, baud 9600, parity none, and 1 stop bit. Smithd pointed out that 0 cannot work as a calling ID and the CAL 3300 doesn’t follow Modbus specifications with parity of none. I needed to change the ID to 1 and use even parity. He was also correct that I needed to set a property node to RS485/wire2-Auto. Sundown thankfully provided his code which allowed me to see how to write a new set point to the CAL 3300. The last error was with my wiring. I kept searching for cabling configurations because I thought there had to be an error there since nothing was working with all the help I was getting. I then came across this article

http://www.windmill.co.uk/rs485.html

Which made since to me. That prompted a search under the instrument control forum that resulted in the follow discussion solved by Frabto.

http://forums.ni.com/t5/Instrument-Control-GPIB-Serial/RS485-half-duplex-2-wire/td-p/1668918

My new wiring is:

TX/RX+   To pin 4 and 8

TX/RX-    To pin 5 and 9

Gnd         To pin 1

Thanks to all for the help. Sundown can you mark this topic as solved.

[francoisbeulz]

Hello,

I am a beginner using Modbus and if I could see these VI's it would be very helpfull, but i am using an older version of labview, could you please post the screenshot of these VI's ?

[erknoebe]

Did you look at the two png files from the previous post?

[francoisbeulz]

Oh yes sorry I didn't see it was png files, it will help me i will try again tomorrow.

[francoisbeulz]

I've made a post here ( but  in french ), if you can have a look please it would help me : http://forums.ni.com/t5/LabVIEW/LV-Modbus-library-1-2-1-Error-code-6101-timeout/td-p/3153674/highlig...

[erknoebe]

Hey Franco,

Read my post about the solution. Attached are png files on the read function. This is easier to accomplish. Next reply will have the write function.

[erknoebe]

Write function.