Communication to PR54-11 using LabVIEW

I have a PR54-11 with each port connected to the TCA9546 Mux units. Each of these Mux connections is connected to 5 SHT25 units. I have read the commands for the SHT and TCA device, so I know how to each of those devices and read the data. What I am not clear on is how to address\switch to each port on the PR54-11 so I can read just Port 1, then Port 2, etc. What are the commands for that switching? I am using LabVIEW so need to know the commands to read write to the serial port.

Also, I don’t understand how the address of the device relates to the board address. For example the SHT25 says its I2C address is x80, but on your board it says it is x40. Same with the TCA its I2C address is xE0, but the board says x70.

@ryan1 can you comment on this

the correct address will be the address you find during I2C scan.

If I have two SHT25, one on port 1 and another on Port 2 of the PR54-11. How do I talk to just the one on Port 1 since both SHT25 use the same x40 address?

Hi Paul,
It would be a good idea to start with the I2C Scan function and get it working.
This will return I2C address of the Mux, do not plug in the SHT25 at this time.
When you scan, you should see the I2C address of the Mux appear when using software.
I believe we have commands for controlling the Mux in our software, and you may be able to select ports and issue multiple scans. The I2C address will appear when the SHT25 is plugged in and the correct port is selected. Please start here before you dive into the programming, we have full source, so finding the commands in our source will be very easy.

Another comment on this topic, the MUX will always appear in your port scan, when you plug in the SHT25, it’s address will also appear if the MUX is correctly switched. You will essentially tell the mux to switch to a different port and talk to the SHT25 on the selected port. The MUX will always respond, but devices connected to the MUX will only respond when you select their individual ports.

Where do I go to change the ports for the TCA?

Use “I2C Quick Scanner” to see what is on each port.
In the case of the PR54-11, you include the port number with your I2C command and it will handle routing for you. Also, for your reference, there is a detailed explanation of how it works in the documentation:

I found that document earlier and that is what I needed to switch the ports xBD (x01 thru x08). I was able to use the COMM Operator program to test the read\writes and get the message structure correct. I was able to R/W these bytes in LabVIEW VISA to the device.