Cannot get RS-485 2-wire auto to work

[John_M]

Thanks KC,

I will investigate the resistance when I get some time, for now I'm using a work around so I can get the code up and running. 

I have tried the connection both with and without a ground and neither worked. 

[John_M]

I did get this to finally work today! I ended up changing the PXI card to a free slot. I left the default settings and set the 2 wire auto mode using a property node in the program and it works. I still have to go back and determine if it's the slot or the settings that were causing the issue. 

Thanks to everyone for the help 

[K C]

Hi John,

Nice to see things are working ok.

Strange, I use a PXI-8431/2 (and PCI-8431/2) and set the mode in MAX to 2 wire auto. I did not use a property node to set the mode and it works just fine.

[Mike_Hu]

The very similar problem when using the PXI8431 card for RS485 communication: here has another usb to Rs485 card, and i set the two 485 card two wire mode,(for pxi8431 set two wire auto mode, have short the pin 4 and pin 8, pin 5 and pin 9), then the usb card send message to pxi card, and the pxi card can NOT receive anything, however, the pxi card send message to usb card, the usb card can receive the correct message. I have change the pxi card to a new slot, but the same result.John,i will be very appreated if you tell me how to do it. For I think we met the same question.

[JasonSmith]

There was a problem in NI-Serial 3.5 which could prevent the wire mode configured in MAX from being set properly, Which is why he property node worked. If you download and install NI-Serial 3.6 this should be resolved.

[Med1can]

resolved