Labjack serial comms


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LabJack state that serial comms are possible with their device;

The UE9 has a UART available that supports asynchronous serial communication. Currently, the UART connects to the PIN2/PIN20 (TX0/RX0) pins on the DB37 connector. On a future UE9 hardware revision, it is expected that the UART will appear on FIO/EIO lines after any timers and counters.

Communication is in the common 8/n/1 format. Similar to RS232, except that the logic is normal CMOS/TTL. Connection to an RS232 device will require a converter chip such as the MAX233, which inverts the logic and shifts the voltage levels.

Now I have used one of LabJack's prototyping boards to create an rs232 to cmos logic level interface using a MAX232.

I have an Ocean Controls MODBUS slave gateway that uses RS232 to poll the registers of a Davis Vantage Pro II Weather station every 10 seconds. The slave gateway makes this data available on a second rs232 port using the Modbus protocol.

I need to do this because I am conducting research for a university project that requires the weather station data to be synchronised with data collected form various other sensors, such as water temperature and IR Temperature sensor.

The problem is I'm getting confused as how to poll the Modbus gateway registers (using Modbus function 3) and getting this weather station data into the LabJack which along with other sensor data is transferred into a spreadsheet.

I'd like to hear your thoughts on the best way for me to proceed from here, as I can see no reason why it should not be possible to achieve.

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Why would you want to do this? Why not just get a USB serial port (though I typically recommend Ethernet based), and use DAQFactory's built in Modbus on this port? Going through the UE9 isn't going to give you synced data since the UE9 isn't going to do its I/O at the same time as the serial comms. You'll get much more synced data if you use DAQFactory because DF can actually do both UE9 I/O and Modbus comms on a separate serial port at the same time.

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