RS485 communication with SCAIME CB50X load cell

[JonasM]

I need some help getting communication up with a Load cell from SCAIME (CB50X-DL) I attached the datasheet for that and the USB-RS485 converter I've been using. I also attached the code made in LabVIEW 2021 SP1 and saved to previous version 2019 to start communication.

I've managed to open the connection and write to the load cell (not confirmed that it received the command) and when trying to read the answer I get a LabVIEW error: 

Error -1073807298 occurred at VISA Read in CB50X-DL.lvlib:Set Address.vi->CB50X-DL.lvlib:Example.vi

Possible reason(s):

VISA: (Hex 0xBFFF003E) Could not perform operation because of I/O error.

While I understand that there is maybe some physical error I don't see what I can change.

I've setup the COM device in Windows Device manager.

Wire connections:

SCAIME CB50X-DL

Yellow to green with a 120ohm resistor

white to +12V power supply

Brown to -/gnd of power supply

Green/yellow to GND of power supply

Grey to orange of USB-RS485 converter and green (120ohm termination resistor pin 2)

Pink to yellow of USB-RS485 converter and brown (120ohm termination resist pin 1)

Connections diagram pages:

SCAIME CB50X-DL can be seen on page 5

USB-RS485-WE can be seen on page 7 section 5.1

In the project and library there is an example.vi that I have run to test the communication. This already fails at the set address command.

[JonasM]

Adding Bias resistors made the Read operation fail on timeout instead. The command was Set Address with parameter ? which is supposed to be querying what address and serial number the device have.

[JonasM · Accepted solution]

Using a RS232 to RS485 converter did the trick.. sort of...

I used a ATEN IC-485SI converter and a USB to RS232 device to communicate with the load cell.

ATEN converter had to have state DCE so I guess the Load cell is a DTE. It's not stated in the manual.

T-ON, R-ON mode was needed to be able to read any data back from the load cell. However in this mode I also read back the bytes I wrote to the load cell as it's 2 wire mode. That was quite easy to mask out though so for now this is what I will go with.

Would still be interesting to have the USB-RS485-WE-1800-BT working but not sure what is required in the software to get it up and running.