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Automate temperature controller

I'm trying to use labview to automate our furnace using a Yudian 518p controller.  I need it to go up to a specific temperature and hold it for a specific time, then at a set rate descend to another specific temperature and hold it again for a set time.  Can someone please help me get started on how I would go about doing this?  I wasn't able to find a Yudian driver for labview.  It has an rs-485 connection and I'm using a USB converter to connect it to the computer.

Thank you. 

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Message 1 of 31

Hello pavelcarbon,


As we do not have an instrument driver for your instrument, you can either request one (which would potentially take a long time) or, you will probably have to learn what the specific commands are that you need to pass to the instrument.  All of your communication to and from the device will be through NI VISA.  If there is something specific about NI-VISA and its programming, please feel free to post it here.  Otherwise, you might want to try contacting Yudian to see what commands to pass.  Either them or perhaps a manual for the device.

Field Engineer
Message 2 of 31

Did you ever find out what codes are to be sent pavelcarbon?

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Message 3 of 31

Hey Kenneth,


You may want to contact the manufacturer with that question, as the commands are sent to their device with the RS485 protocol where as NI-VISA is a method of delivering those commands.


The documentation on your device could be found here, where the PDF listed on the page has more in-depth specifications.



Jake G.
National Instruments
Applications Engineer
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Message 4 of 31

Dear Kenneth and Jake,


The communication protocol of YUDIAN instruments is here


There are two version with a little difference in parameter table. It depends on the instrument firmware version.


Our software engineer has tried to develop NI-VISA with Yudian instrument.


It would be great If there is any instruction for us to develop the driver of Yudian RS485 communiction. 


Chris Chak

Yudian Automation Technology Co., Ltd.

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Message 5 of 31

Hi Chris,


We have several tutorials and helpful documents for developing an instrument driver. One tutorial you might want to start with is Developing LabVIEW Plug and Play Instrument Drivers


If you're planning on communicating via RS485, you'll probably want to take a look at some of the serial communication example programs as well. There are several in the LabVIEW Example Finder and many are available online as well, such as this one.


You might also want to take a look at the Instrument Driver Developer Program   as it appears you'd be making the driver for  your own instrument.


I hope this helps get you started on the right track,



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Message 6 of 31

I have developed a short code that seems to work with the 518P. This sends the write command for a controller at address 4 and returns the SP and PV. Use the airbus protocol instructions on their website to modify accordingly. I will be developing a stripped down driver for myself to at least read SP, PV from any address. This still needs the responce converted from hex to floating point.

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Message 7 of 31


I have problem with starting the communication process with my YUDIAN 518 with LabVIEW through roger UT-2USB converter. The COM led on YUDIAN controller is not responding after I send package from PC. Maybe some activation on the YUDIAN controller need to be done before start to communicate? Do enyone have some working example of .vi? The one from nasu coleque seems not working with my hardware. Thank in advance.

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Are you able to establish any communication with the device (separate from LabVIEW)?  Can you communicate to the device from MAX?

Wayne T. | Application Engineer | National Instruments
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Message 9 of 31

If the command is not properly created, the Yudian device does not respond. From page 7 of the manual:

"If the instrument does not reply after the maximum response time, there is some problem, for example, invalid instruction, communication line malfunction, error communication address or the intrument is power off."

From looking at nasu's image of his vi, he has not included the ECC in the byte string which should result an "invalid instruction" and thus produce no response.

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Message 10 of 31