PLCENGR014
Member
Hi all!
I am hoping to find some help understanding the ABB VFD Connection to my Rockwell PLC.
I have set up the VFD parameters based on the provided ABB worksheet for the ODVA extended set of parameters. I have uploaded an image of the parameter settings from the ABB Spreadsheet.
My issue comes with the speed reference control however. In the PLC, I send a speed reference command over ethernet to the VFD. For example, 100 RPM. I then read that reference BACK from the VFD to verify the correct speed reference has been sent. The two should match exactly. But they don't. If I send a reference of 100 RPM, as a data type INT (as specified in the ABB documentation for the transfer) I get back a value of 1111 RPM. Now, I assume that the value is a modified value, corresponding to 111.1 RPM, which matches the other data transfers I see, so the decimal value is not my concern.
My issue is that if I tell the VFD to spin at 100 RPM, I should get a reference back of 100.0 RPM (1000). With the extra 11.1 RPM I am getting back, this throws the whole system out of tolerance.
So, I am wondering if there are any ABB & Rockwell experts out there who can enlighten me on where the extra 11.1 RPM comes from, and how I can scale or remove it to get my references sent and received to match!
Thanks in advance!
I am hoping to find some help understanding the ABB VFD Connection to my Rockwell PLC.
I have set up the VFD parameters based on the provided ABB worksheet for the ODVA extended set of parameters. I have uploaded an image of the parameter settings from the ABB Spreadsheet.
My issue comes with the speed reference control however. In the PLC, I send a speed reference command over ethernet to the VFD. For example, 100 RPM. I then read that reference BACK from the VFD to verify the correct speed reference has been sent. The two should match exactly. But they don't. If I send a reference of 100 RPM, as a data type INT (as specified in the ABB documentation for the transfer) I get back a value of 1111 RPM. Now, I assume that the value is a modified value, corresponding to 111.1 RPM, which matches the other data transfers I see, so the decimal value is not my concern.
My issue is that if I tell the VFD to spin at 100 RPM, I should get a reference back of 100.0 RPM (1000). With the extra 11.1 RPM I am getting back, this throws the whole system out of tolerance.
So, I am wondering if there are any ABB & Rockwell experts out there who can enlighten me on where the extra 11.1 RPM comes from, and how I can scale or remove it to get my references sent and received to match!
Thanks in advance!