Read/Write to GE-Fuji Motor Drive via Modbus and RS-485

[ranger]

Attempting to communicate to a GE-Fuji Motor Drive (AF-300 G11) via Modbus.  I am using a RS-485 to RS-232 converter connected to serial com1.  These seem to be a fairly common motor drive, and I have found some old threads but am hoping someone would be willing to share some example code of how to read the frequency and set the frequency, I would be most thankful.

I have tried the NI Modbus VIs and some other VIs I used for 'talking' to a flow meter via modbus/RS-485, but still no luck. 

Thanks,

Steve

[Wayne.C]

Steve,

GE-Fuji drives usually ship with free communication software.  I would suggest trying to communicate with the drive using the factory software as a means to verify operation of your com port/232-485 converter and communications cabling.  After this is working, then I would go back to the NI-Modbus functions.

[Justin_E]

Steve,

Modbus communication is essentially serial communication, so you may want to perform a loopback test on your converter to make sure everything's working properly on that end. Setting/reading the frequency shouldn't involve much more than writing or reading a certain register/set of registers, so I'd take a look at the MB Serial Master example as a starting point. You'll likely want to develop your own program for communication though.

[ranger]

My drive did not come with any software, however after doing some googleing, I found a demo for a Modbus master simulator that allowed me to determine that my serial port, RS-485 and cabling is ok.  I belive my issue is that the register addresses listed in the drive manual need to be converted to something that I can send via Modbus.  For example, the manual lists....Address: 2054, code: M06, Description: actual freq.  If I read from address 2054 using the Modbus slave simulator, I get an error stating non-valid address.  So I experimented and determined that reading from addresses 0 through 20 or so is valid, but I have no idea how the addresses 0 thru 20 map to the address listed in the drive manual with a range of 2049 thru 2096.  Any suggestions?

[Justin_E]

Hey Steve,

Keep in mind that Modbus requires a very strict way of sending commands, so you'll want to make sure the values you're sending to the modbus write function are of the appropriate byte length. Past that, I'd post the drive's manual here so we can look at it to see if we can help you out. Also, it'd be a good idea to check out the modbus protocol specifications to familiarize yourself with how the messages are structured.

[ranger]

The manual for the drive can be found at:  http://www.geindustrial.com/publibrary/pubLibResult.jsp?famId=13&prdTypeId=5540&subTypeId=316&src=cw...

The manul is the last item listed on the page: 'AF-300 P11 Var. Torque Freq Adj Drives'.  Once the manual opens up, the modbus info is located in chapter 12.

My error must be something simple, but I haven't been able to figure it out yet.  Looking at the Modbus Protocol Spec, I believe my error is with the start address, but I'm not sure.

Steve

[Justin_E]

Hey Steve,

According to the manual, the device works as a Modbus slave. You should look at the Modbus Master example, as your computer will act as the Modbus master. 

[Luke-Jenson]

Give this link a try. Has lots of info about G11/P11 drives.

GE / FUJI G11 & P11 Drives

[Eb1]

hello, did anyone have any luck figuring our the addresses on the manual compared to what we nornmally use setup on a typical controller?