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Modbus Rtu On Danfoss


gmor

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Hello Glenn

 

Welcome to the forum.

 

What version of CScape are you using?

 

Best regards,

Mark.

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Hi Glenn

 

In version 8.8, you can set the modbus master to 6 digit addressing, it is an option.

 

Firstly, I hope that you are using the scanner option for Modbus Master. This is got to via the top menu, "program" then "Protocol configuration"

Select Modbus Master for the serial port that you are using. Set up the hardware configuration under the network button, then set up you device (FC202) under the device button (add device), set the network address (ID) to match the ID on the drive and select device type as "Modicon PLC 6-digit Addressing" then add your scan list under the scan list button.

 

You do not need any ladder logic to make this work, although I would normally set up a status register for each device and use that to indicate a comms error.

 

Make sense?

I am not sure what level you are at, so I appologise if I am stating the obvious. If you want more detail and sample code, let me know.

 

Best regards,

Mark.

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Thanks Mark, the setup you mentioned I have previously tried, along with a few others. Sample code would be good, then I can see whether it is my setup or the cable & port connections. looking at the status register under Data Watch, I keep getting comm errors.

 

regards,

Glenn

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Hello Glen

 

I have attached some sample code, (not tested on a drive but should work) that will show the basic set up.

This requires that the drive is set up for MODBUS RTU and ID = 1 9600 baud, 8 bit, 1 stop and 0 parity.

 

The drive is connected to MJ2.

pins 1 and 3 are linked as TX+ and, 2 and 4 are linked as TX-, and pin 6 is earth.

 

Let me know hw you get on.

 

Best regards,

Mark.

FC202_basic_comms.zip

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Hello Glenn

 

I am able to down load and open the file without problems.

 

I have uploaded the unzipped file to a directory on this site at : http://www.lmpforum.com/uploads/FC202_basic_comms.csp

 

Try this and let me know.

 

Best regards,

Mark.

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Hello Glenn

 

Thank you for the update.

 

One of the things to be careful of, is to make sure that you download as 32 bit (2 word) and 16bit as appropriate.

I would suggest that you add each parameter, one at a time and prove it before adding the next.

I have had issues with "16 bit" that had to be treated as 32bit to prevent errors.

 

Best regards,

Mark.

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  • 6 years later...

Hi,

I have problems with Danfoss FC 102 VFD-s.

I can t read anything from them in Vijeo designer.

Anyone can help me, please.

I want to read frequency, current, power and I want to write the frequency reference.

I'm able to read values with Mtester but I cant read them with other softwares.

 

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Hello Finetti

 

I have not used Vijeo, but the concept is the same as other Modbus devices.

The problem if you are using 40,000 based addressing, is that the correct range of this addressing is 40001 to 49999 and the registers that you want to read fall outside this range. (Danfoss function number times 1,000 plus 40,000)

 

If you use the 40001 based addressing, the registers that you want to read are typically in menus 15 and 16. For example, to read the frequency, you need to read 16.13 Using the Danfoss formula, the address to read is 16.13 x 1000 + 400000 = 16,130 + 40,000 = 56,130 which is greater than 49999 so it is outside the traditional range and will not be allowed by many systems.

 

Fortunately, there is also the possibility of using 6 digit addressing with some systems. The formula now becomes Danfoss function number times 1,000 plus 400,000, so to read the frequency, we read 416,130.

 

The alternative, is to use function and offset and the Danfoss offset is the Danfoss function number times 1,000 - 1

To read the frequency, use function 3, offset 16129 (in decimal)

 

You need to determine the options that the software offers you and use the appropriate option.

 

Best regards

Mark.

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  • 1 month later...

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