Modbus communication between Delta PLC and Danfoss VFD

To execute MODWR and MODRD instruction of Delta PLC, I need address of register in VLT 2800 but I cannot figure out. Can any body help me? I want start, stop and set frequency. Also I want to read output frequency and current.

For example

---||------- MODWR K1 Address D10

What should I write in place of "Address" to set a certain frequency?

See pages 18-20 (pdf) in the VLT 2800 Modbus manual at the link below for Modbus register addresses:

http://files.danfoss.com/download/Drives/MG10S202.pdf


I have no idea whether your logic syntax is good, bad or indifferent.

danw said:

See pages 18-20 (pdf) in the VLT 2800 Modbus manual at the link below for Modbus register addresses:

http://files.danfoss.com/download/Drives/MG10S202.pdf


I have no idea whether your logic syntax is good, bad or indifferent.

Click to expand...

I was not able to communicate with the command MODWR (may be this instruction only valid for delta VFD) but can communicate with PLC Link. In pages 18-20, memory maps are given for VFD parameters which now I can read and write. But I still cannot figure out the address of Control Word (CTW) and Status Word (STW) which I need to run/stop VFD at certain frequency.

An example in Appendix A on page 32 (pdf) shows an example of the control word and reference speed written with Modbus Function Code 0F to Coil address 0000 as 32 bits or two 16 bit Modbus registers.

Pages 21 & 22 show the format of the control word.

Read/Write coil data using Delta Easy PLC Link

danw said:

An example in Appendix A on page 32 (pdf) shows an example of the control word and reference speed written with Modbus Function Code 0F to Coil address 0000 as 32 bits or two 16 bit Modbus registers.

Pages 21 & 22 show the format of the control word.

Click to expand...

0000 is the address of coil but not of register. According to MG10S202 manual, there is no special register for control word as I can see that all other registers except those for parameters number are reserved unlike Danfoss FC51 drive. For modbus communication using PLC Link of Delta PLC, I can only read/write from/to holding registers (I have very limited knowledge about that as this is my first work using bus communication). So can you please tell me how I can read/write coil data by using delta PLC DVP12SE?

The example shows writing 32 bits to coils, not to Holding Registers.


The table below (poor example, but the only one I have, it is a vendor-specific table with defined analog outputs, which are Holding registers) shows the most commonly used Modbus commands. Function 0F hex (16 decimal) writes to multiple registers, where each registers is 16 coils.





The Coils reside in memory area that starts at 000000. When the Function code is specific to reading/writing coils, then addressing starts at the memory area for coils, not for Holding Registers. The leading numeral 4, as in (4)00001, defines the register as a Holding register, but the leading numeral is not part of the Modbus packet; it is the Function 03 that defines the indexed offset 'address' for Holding Register memory area.





You'll have to interpret the command word bit-by-bit to see what it's doing, and make appropriate changes, but the example clarifies that the command word resides in a Danfoss as a coil register, not as a Holding Register.

hello...
i'am new here.
help plese.
How can I send an FC51 to sleep?
thanks

Hello pepe140, I recommend you start a new thread instead of using this old one from 2019, and that you describe in it what you have and what you want to do in more detail.