Error 1671 Python Node

[Operandus009]

Hi,

Labview 2018 user here. For some time, I was using Labview with Matlab script node to throw in some maths. I decided to switch to Python since the 2018 version of Labview supports it.

I tried some very basic tests ("Hello world" and some others) but when it comes to use one of my scripts (reading a three columns txt file), it sends me an error message :

Python Node in testlecturefichier.vi<APPEND>

Python returned the following error: <class 'SystemError'>
..\Objects\listobject.c:189: bad argument to internal function

The function is running flawlessly with the ipython console but not with the Labview node.

There are some additionnal infos :

- 3.6.2 python, 64 bits

- Labview 2018 64 bits

Maybe there is something obvious I missed. Can someone look through my code and maybe tell me what is wrong ?

Thank you in advance for your time.

[wiebe@CARYA]

Did you search the forum? This has been posted quite a few times before.

search the forum...

There are also (at least) 3 related knowledge base articles:

Error 1671 Occurred at Open Python Session

Error 1671 in LabVIEW When Calling Files Using Python Node

Error 1671 Using Python Script Stored on Network Drive in LabVIEW

[Operandus009]

Thank you for your answer.

Yes I searched for answers but none of the previous topics deal with my specific error. But I am wondering if you read my query before posting ...

[Operandus009 · Accepted solution]

Ok, found the error.

I was expecting an array but I was trying to return a list in the script so it wasn't working.

[Will_S.]

Just to add to this answer, since I just went through this: LabVIEW apparently can have trouble converting a list to an array unless it is explicitly built as a list.

For example, even though a slice returns a list, LabVIEW can give you Error 1671 if your python function returns it directly:

# Can cause Error 1671 in the LabVIEW Python node
def myfunc():
    return myData[:6]

Instead, do this: 

# Does not cause an error in the LabVIEW Python node
def myfunc():
    returnData = []
    for x in range(6):
        returnData.append(myData[x])

    return returnData

[derGogo]

Hum. I think I'm having exactly the same problem. Only I'd like to avoid modifying the python script, because 1- it's not mine, 2- it is used by other apps.

Can you think of a way to solve that on the Labview side?

my Python:

derGogo_1-1687510043937.png

my labview code (right) and error (left), in which the keyword hinting to the same problem as yours is "Failed when trying to convert field into tuple at index 1":

Output as int plus array cluster.JPG