Controlling a VFD with MODBUS for laptop serial port

[jschwei314]

I just want to be able to demonstrate the operation of a VFD with MODBUS.

I am not a MODBUS expert. In fact I know very little.

I am looking for software to make my laptop a Master and control one VFD through my serial port. Then a converter to change RS 232 to RS 485.

Has anyone out there done this.

Super thanks.

 

[dpc]

A quick Google search turns up a lot of apparent options - here's one:

http://www.win-tech.com/html/modbus1.htm

 

[jschwei314]

Mr. DPC,

Thanks for your response I have seen Modscan.

I am looking for someone who has done this. What program one has used and what RS 232 to RS 485 converter was used and some helpfull hints.

J Schweitzer

 

[jraef]

You will need a Modbus register map from the VFD mfgr., then look for the regester associated with speed reference. You can set up a simple Excel spreadsheet to load values into the necessary registers.

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[dpc]

I've used the referenced WinTech software - the demo version would probably work for you for a while.

As jraef says, you need to get the ModBus register mapping from the VFD vendor.

The next recommended step is to see if you can read a few Modbus registers and if the data make sense. Once you can read data, then you can look at trying to do control.

 

[LionelHutz]

B&B Electronics makes converters.

Modscan works OK if your desired application isn't too complicated. You can create a simple custom display type of page with some bar graphs or dial meters. It's just not real nice to write data, basically you get a pop-up box where you enter the value.

I don't know of any other software offhand that would be any better. It's likely that you'd need to program your own application if you want to get fancy.