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Controlling a VFD with MODBUS for laptop serial port

Controlling a VFD with MODBUS for laptop serial port

Controlling a VFD with MODBUS for laptop serial port

(OP)
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.

RE: Controlling a VFD with MODBUS for laptop serial port

(OP)
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

RE: Controlling a VFD with MODBUS for laptop serial port

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

RE: Controlling a VFD with MODBUS for laptop serial port

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.

RE: Controlling a VFD with MODBUS for laptop serial port

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.

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