Modbus NI VISA Serial - Tx%2FRx Error

[Muthuraman]

Hi,

I am using Virtual Serial Port emulator to create a pair of 2 COM ports and to connect them.

I am using the below LabVIEW VI to transmit Mod bus data and Receive Mod bus response using VISA serial VIs.

The NI VISA version i am using is NI VISA 5.o and labview 2010.

But there is no response from the serial buffer and it keeps timing out.

The same VIs looks to be working fine in another location in Windows xp PC.

The controls in the VI has the default value which is used during execution. Any help will be appreciated.

I am attaching the VI, PC configuration and the node throwing error.

The Top level VI is "Mod bus - VISA Communication Error.vi". At the low level, the "AT - Serial Receive" is the VI which is throwing error. Please see below image.

Please help.

Regards,

Muthuraman.

[MarcoMauri]

Hi Muthuraman,

did you try using a serial sniffer, to check what's happening on the bus?

You can also give a try to the NI Modbus library (http://ftp.ni.com/pub/devzone/epd/nimodbus121.zip)

Regards,

Marco