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RS232 Modbus RTU - LabView 2017 RT

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Hi all,

I'm working with CompactRIO 9045. This plc is equipped with the rs232 and the rs485. I need to communicate with two devices in Modbus RTU. 

I have no problems with RS485 (ASRL2::INSTR) communication. This is initialization VI:


I do the same operation with rs232 port (ASRL1::INSTR):


But I have this error:

Error -1073807246 occurred at Property Node (arg 1) in SubVIs.lvlibSmiley frustratoerial Shared Components.lvlib:Configure Serial Port.vi->SubVIs.lvlibSmiley frustratoerial Master.lvclass:Initialize Master.vi->Modbus Master.lvclass:Initialize.vi->Modbus Master.lvclass:Create Master Instance (Serial).vi->readExdSh1.vi

Possible reason(s):

VISA: (Hex 0xBFFF0072) The resource is valid, but VISA cannot currently access it.


The resource can't be occupied...

I have seen all  national guides and tutorial, but I don't find the solution.

Can you help me?


Thank you.



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Do you have ASRL1 open any where else, say in MAX or another part of your program?

Is it possible the CONSOLE OUT switch is enabled which will then use the COM1 port?


Edit: Just noticed after finally finding a picture of the 9045 on the NI Website 👾 that it doesn't look like it has DIP switches for CONSOLE OUT.  So not sure if you can check in MAX to see if its enabled.


<\rant> Its impossible to find anything on the NI website nowadays.  Its gotten so bad, that I now wish they would just create one giant webpage for each product line (cRIO, PXI, etc) that has every single document in pdf format for each piece of hardware in alphabetical order in plain text.   This BS of clicking on something and then having the website perform a search of the website is ridiculous  :frusty:</rant>

Edited by bbean
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