LabVIEW
VISA: (Hex 0xBFFF006C) An overrun error occurred during transfer.
Hi Raj,
@HarshRaj18 wrote:
Could you please check now? Otherwise, I will try on another laptop. Somehow it seems not to change the version. I tried several times.
It changes the LabVIEW version when you use SaveForPrevious…
On your VI: why don't you cleanup the block diagram? Readable code helps to minimize problems!
See this:
- What do you want to achieve with the ElapsedTime function inside the case structure?
- Why is there a wait function inside the case? Placing such wait functions is enforcing buffer overflows in the communication bus!
- Do you really need to write a XLSX file? Would a simple CSV file be sufficient? (Writing CSV files is often much faster…)
- You forgot to provide a typical device message, so see my string handling only as suggestion for possible improvements. There's room for more improvements…
- …
One of my suspicions was correct. Each time you write your command, the device sends the OK response and then the data. So you need two reads after the sending the command. The first read will be the OK and the second read will be your data.
I just took longer to do a clean up than I should have. But here is how I would set this up. The main thing I did here was create a subVI for sending the command. The insides of that subVI are concatenating the carriage return to the command (I do not trust the VISA property), write the command, read the acknowledgement, and output if it was an actual ACK. I then use this for the setup and the data request.
Hi,
I could solve the earlier problem and the instrument is logging the data correctly. However, I want to use this data logging file to control a PID system. How can I use the same "Flow Modified PID" file (which is already working for data logging) in the file "TSIFlow PID Test" as subVi so that it shows the same value it is reading in the logging file? It reads the Flow, Temp, and Pressure with logging file but when I use it as SubVi, it doesn't read anything in the PID Vi ("TSIFlow PID Test" marked in Blue).
In short, data logging is done but I can't use that Vi to control the PID. I can clarify if it needs more clarification. Thank you.
Hi Raj,
@HarshRaj18 wrote:
How can I use the same "Flow Modified PID" file (which is already working for data logging) in the file "TSIFlow PID Test" as subVi so that it shows the same value it is reading in the logging file? It reads the Flow, Temp, and Pressure with logging file but when I use it as SubVi, it doesn't read anything in the PID Vi ("TSIFlow PID Test" marked in Blue).
You need to OBEY DATAFLOW!
- There should be no loop with a STOP button inside your subVI! Remove the loop…
- You should split the current subVI into 3 subVIs: "init COM port", "read data" and "close COM port". Do the loggin in your MainVI (or as separate subVI)…
- Other option: run the current subVI in parallel to your MainVI and communicate between both VIs using queues or channels…
Important: set a better icon on your subVI… (Open icon borders are really annoying!)
@GerdW wrote:
- Other option: run the current subVI in parallel to your MainVI and communicate between both VIs using queues or channels…
I would go so far as to break up this application into three loops.
1. Data reading loop: Reads the measurements from the device.
2. Main loop: handles the State Machine and PID control.
3. Logging loop: Saves the data to the log file.
The idea here is to use Queues to pass the data from the reading loop to the other two loops who do whatever it is they need to do with the data.
