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odd Modbus error

I'm using LV 2015, 32bit on two W7 laptops, and a cRIO 9036 chassis. I have the same program, configured differently, on all three targets. One laptop has been talking Modbus TCP to an industrial PLC-type controller for years, using a module I wrote specifically for that PLC instance. I recently put that module down on the cRIO. It now talks Modbus TCP to the same PLC at the same time, no problem, no errors.

Then I tried to put that same module on the 3rd target, the second W7 laptop. It returns data, which appears to be correct. But every read of a Modbus channel also returns this error:


Error 1 occurred at :  Modbus in MICAS  Possible reasons:  LabVIEW:  An input parameter is invalid. For example if the input is a path, the path might contain a character not allowed by the OS such as ? or @.:  SubVI in SubVIs.lvlib:TCP Master.lvclass:Protocol>SubVIs.lvlib:IP Data Unit.lvclass:Write ADU>Modbus Master.lvclass:Read Input>Modbus>MICAS


The firewall on the 3rd platform (2nd laptop) is turned off. All three platforms are plugged into the same Ethernet switch.


Any ideas what Error 1 means in this case? I did think that maybe three connections was "marginal" for the controller, so I did try stopping the first laptop and the cRIO and running JUST the 2nd laptop, but it still gets an error!




David Thomson Original Code Consulting
National Instruments Alliance Program Member
Certified LabVIEW Architect
Certified Embedded Systems Developer
There are 10 kinds of people: those who understand binary, and those who don't.
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I found a few different instances where that error comes up. They are slightly different scenarios, but the error seems to be the same. 


LabVIEW Error 1 or 6: Input Parameter is Invalid:


Error 1 Occurred at Open VI Reference:



Let me know if this helps or you have tried these steps already!




-Brian J. 

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