Error 56 Modbus RTU RS485 VLT Automation Drive FC 302

[Lappwaschen24]

Hello,

I'm trying to connect LabVIEW to Danfoss VLT Automation Drive FC 302 via Modbus RTU and RS 485. When i do this, i get Error 56 (Timeout). I tried several Codes.

Both Codes can be found in the following YouTube Videos:

LabView "Modbus RTU" Danfoss FC302 Tutorial (youtube.com)

Simple Modbus Code Part 2 (youtube.com)

In both Codes, i got the same Error Message.

The first Link has exactly the functionality i need!

I can confirm that Unit ID, Baudrate, Flow Control, parity and stop bit are correct, because i was able to get a connection threw the same interface with the MCT 10 Software (a Software from Danfoss) to the VLT.

I can see the Interface in NI Max. Nevertheless i reinstalled NI VISA and NI MAX (i can still see the interface). I still got the Error Message 56.

Also i set the time for a Timeout to 120s. This did not change anything. I still get Error 56.

Do you have any idea how to fix the problem?

Thank you for your input!

[Curr93]

Hello dear friend

try:

1) turning off reentrancy. It is possible that a race condition is occurring that is causing the network to become busy and time out when writing or reading.

2) another library tool called plasmionique modbus master toolkit from VIPM

3) may be another process had grabbed the port