CANOpen parallel reading from the same device

[renek]

Hi,

i want to read and write parallel to the same device on the can bus. I write a small test programm. but if i want to read parallel i become an error. It is possible to read/write to the same device in multible threats?

The final application has two threats...one reads values and the other write values.

I have the CANOpen NI PCI 8531 Card in my PC.

thanks,

René

[WolfgangSimeth]

Hello René,

first of all, what error do you get and which function throws that error?

Best regards

Wolfgang

[ThreeLions]

Hello René,

I agree that the error code and useful scrrenshot will help us to figure out this question.

According to your description and the attachment, I suppose the error occurred when the Read.vi(on the lower thread) started to work during the Write.vi(on the upper thread) running. If so, it makes sense because it cannot do 2 works in the same interface simultaneously. In other words, a thread cannot break off the other thread. After all, whatever Read.vi and Write.vi needs time to execution.

For running a PCI 8531 with 2 threads, you should control the data stream by Error Cluster between the 2 threads.

Thanks!

[renek]

Hi,

thanks for the answers. I do some testing. I insert some semaphores at the beginning and the end of a base read funktion

Is this also a good way to synchronize 2 or 3 tasks?

[WolfgangSimeth · Accepted solution]

Yes, you can use semaphores but serializing the threats would bring the same result and the code would be much easier to read. Just do the writing/reading and after that task is done, do the reading/writing. Use error clusters like proposed before. Your application could look the screenshot attached.