data rate issue with Labview VISA Read and multifunction module

[Dennis_Knutson]

There;s a couple of problems. One is that you don't need the VISA Write since you are not writing to the transceiver. You only want to do a VISA Read. Second, you need to have a value wire to the byte count of VISA Read. If you know the number of bytes in each transmission, you can use a constant here. If you don't know, you could use VISA Bytes at Serial Port to determine how many bytes are available but then you'll probably need to do some parsing if you read multiple transmissions at a time. If you want to read continuously, then you want to put the VISA Read inside a while loop. I've attached a picture of the minimum modifications you need to make. You will probably want to modify this further. This example will only display the very last frame read from the serial port. You might want to use a chart to display the current and past readings.

[JohnM 64]

I took a look at the Serial VI you made, and I only see one thing that looked like it needed to be changed: you have a VISA Write function after the VISA Open, but you have no input wired to it. I do not believe you even need the VISA Write, because I think you are only reading information in. I would also encourage you to take a look at the serial examples that ship with LabVIEW, by going to Help and then Find Examples... If you search for serial, several example programs should come up that will help you with your program.

Good luck with completing your application!

John M
Applications Engineer

[danadu]

Thanks all for helping. I'm waiting for the Max3238 chip to come and then do testing, hope it will work. In the meantime, I wish you all have a Merry Christmas and a Happy New Year. Thanks,