Here is the link to VDSoft program is located at
http://www.delta.com.tw/product/em/drive/ac_motor/download/software/Delta_VFDSoft%20V1.48_20130903.zip Yes VDSoft will let you read all parameters from the from drive. I posted up a previous txt file.
I have a lathe that I can run in by hand or by CNC. I can give up manual operation. I have limited space and have to take off the keypad when covering the VFD. I have the keypad installed. I also included recent photos of the VFD and RS-485 connector. I like yours much better.
I am wondering if the manual configuration is the issue. Maybe the VFD senses the manual operation and goes to 0 from the VFD firmware. I wonder if this could be the fall back option you mentioned. Which doesn't make sense because VDSoft can control it with no issues, but that might be special to VDSoft.
There are two switches on the VFD AVI/ACI and NPN and PNP the documentation is lacking on what these are called and what they do. I just looked at the book and switched them to match the wiring.
On my old laptop I have a USB converted. On the desktop, I have a physical serial port. I did toggle the RTS on and off and in modbus test it worked correctly. I just left it off.
Ya-Nvr-No I am trying to run the motor direction and RPM with the Modbus configuration. I looked at the Delta-EL series manual and they are the same. You should be able to control the EL with the same configuration.
I will send out my VFD parameters and if you could check your switches on the VFD that might give me a clue on the issue. I will research removing my manual controls.