RS485 timeout error 6101.

[77maxmustermann]

Sup Guys

I'm using a Omega cn7800 and I want to use it in my lab view program

it is being connected to my computer via a RS485 to usb converter.

Sadly when I tried to use the Example VI it I got an error. I've searched on internet for a solution but sadly there were none

[arteitle]

All we can tell from your picture is that the Modbus communication is timing out, but you already knew that. Please attach your actual VI, then we can get a better idea of what might be the problem.

[77maxmustermann]

Thank you for answering:

It's an example VI for the Omega CN7500 driver which I'm using in the hopes of being able to display the fructuation of the temperature in view lab with a CN7800.

[arteitle]

I see, presumably the code is good if it's a shipping example from Omega. I see it's missing a lot of subVIs, but don't worry about those at the moment. I'd focus on the settings of the controller and the connection to the PC. Are you sure you have the software and the controller both configured for the same baud rate, parity, and slave address? Is Modbus enabled on the controller? How is the USB-RS485 adapter wired to the controller? Do the CN7500 and CN7800 use the same Modbus addresses to store the process temperature?

[77maxmustermann]

First I want to excuse my self for my tardive Responce. Sadly during the week end I didn't have access to this computer.

It is wired via a RS485 to USB adapter (tM-7561).

Double checked Parity Baud rate are the same.from

the RS-485 Communication is with the MODBUS ASCII/RTU communication protocol.

What do you mean exactly by " Is Modbus enabled on the controller" .

From my understanding CN7500 and 7800 are basically the same the adress should be same.

I already contacted Omega to be sure (that means that this driver is compatible with the 7800 as well)

[arteitle]

Be aware that Modbus ASCII and Modbus RTU are different protocols, so the device and the software both need to be configured for the same type. As far as the USB-RS485 adapter wiring, what specifically are the connections between the adapter and the device, what are the terminals labeled at both ends and how are they connected together?

[77maxmustermann]

They were the same connection type. Anyhow I ditched the program that Omega made and used an instrument someone made in their spare time instead. it worked from the get go ! Thank you for your help that was really nice 🙂