Modbus communication Error

[Randheer]

Hi All,

I'm trying to communicate LabView(DSC) with an LG PLC which is modbus supported. The hardware setup is like, a RS232 cable is connected to PLC and the other end of the cable is connected to a RS232 to USB converter (Because the Laptop doesn't have RS232 port) which is connected to Laptop USB port. I tested the communication with Modscan32 and with another SCADA and were successful. But, when I tried connecting to LabView I'm getting an error, " error code: -1967353900. The Modbus I/O server failed to allocate a serial port." . I restarted the laptop and tried, but that error persists.

Yes, I have gone through the link given,  http://zone.ni.com/reference/en-XX/help/371618D-01/lvdschelp/dsc_modbus_trbsht/ , but wasn't helpful...

Please let me know the steps to follow to overcome this error.

Thanks,

Randheer

[subbzz]

hi..

as a quick thought.. please exit the modscan32 before you communicate through LV because the port will be blocked by the modscan instance..

and also please make sure with the serial port settings like the baud rate, parity etc with the PLC and the Addresses match.

[Randheer]

Hi,

Thanks...

Yea I have closed the Moscan32 too, that is why  I mentioned that I have restarted the PC and tried.

Serial port settings like the baud rate, parity etc with the PLC is correct, that is why I was able to communicate with PLC through Modscan initially, and I have used the same port settings in LabView.

[Randheer]

LabView version is 11.0 and my lap's OS is windows7.