Modbus RTU - RS232

[SimoneMarchettiEDA]

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 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.lvlib:Serial Shared Components.lvlib:Configure Serial Port.vi->SubVIs.lvlib:Serial 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.

[RavensFan]

That error usually means some other program has the serial port open.  Once it in a while it might be an early instance of LabVIEW that opened it, but didn't close it cleanly.  In that case, closing LabVIEW and re-opening will solve the problem.

[SimoneMarchettiEDA]

Hi Revens,

I have dove it but I have problem again. I create a project with only VI and I have problem. 

I think that there is a default process that occupies the rs232 port.

[RavensFan]

You'll need to figure out what that default process might be.

A common error is for someone to open up the manufacturer's software for communicating with the device, and failing to close it out before using LabVIEW to communicate with it.

[SimoneMarchettiEDA]

Hi Ravens,

thank you for reply.

I haven't active process or application. I don't insert cable. I want see that I have an available com port.

[alamanna]

Hi,

you can find the possible causes as well as the solutions to the specified error in the following document:

Error -1073807246 Using NI-VISA
https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019NeQSAU&l=it-IT

Regards,

Alessia