Showing results for 
Search instead for 
Did you mean: 

modbus communicate over USB




I am trying to communicate to an APC UPS over USB using modbus. This manual discusses how the protocol works with the UPS. 


Does anyone know how to setup a vi to send a given message (register 130 in the above manual) and receive the response all over USB using modbus? It looks like a particular driver needs to be downloaded as well to allow for interrupt transfers.



0 Kudos
Message 1 of 2

Hi MNR001,


I'm not entirely sure if you can use just USB. My suspicion is that you would have to get a USB to serial adapter. On top of this, there are a few libraries that one could be using for programming Modbus in LabVIEW, the Modbus Library for LabVIEW which is a free download from the NI Website (found here: but is note supported by the Applications Engineering Team, or the Modbus API that comes with the LabVIEW DSC Module or LabVIEW RT Module. If you have access to either the LabVIEW DSC Module or the LabVIEW RT Module, look into the API. If you don't, it may be worth checking out the Modbus library.



Peter George

Applications Engineer

National Instruments

0 Kudos
Message 2 of 2