data logging using LVM - file

[DFGray]

LabVIEW tables can get very slow if you load them with a lot of data.  The solution is to not load the table with lots of data .  You can do this by realizing that the table cannot show all your data at once.  Instead of using the table as a data buffer, use the file.  Only read the amount of data and display it in the table if it will actually be shown.  The hard part is the scroll bar so you can scroll through your data.  If you have LabVIEW 8.0 or above, there is a scroll bar control you can use to select what portion you want to display.  If you have an earlier version of LabVIEW, let us know and we can give you the standard workarounds.  Run the scroll bar using the event structure.  If you arrange things right, your user will never know that the scroll bar doesn't belong to the table.  Using this method will allow you to get good interactive speed from your program.

If you run into problems, let us know.  Good luck.

[S_Kanchap]

Thanks for prompt reply.

I have LV 7.1

Seeking your valuable advices.

[DFGray]

First, do not show the scroll bar on the list.  You will never have more data in the list than it can show, anyway.  I will give you three options, ranging from easy to hard, all of which I have seen implemented.

1. Use a slider control for your scroll bar.  You can customize it to look a lot like a scroll bar.  Use Advanced->Customize on the control pop-up menu.  UI is then fairly simple, since you can use the slider position to determine what part of the data in your file to fetch and display.
2. Use the scroll bar from a classic listbox for your scrollbar.  Color the frame and background transparent so that only the scrollbar is visible.  Fill the listbox with as many values as the pixel height of the scrollbar (that is your maximum resolution).  Getting values from the scrollbar is somewhat convoluted because there is no event fired when the scrollbar is moved and a MouseMove event on the listbox does not occur when you are over the scrollbar.  So, create a boolean in a shift register of the loop containing your event structure.  On MouseDown on the listbox, set the boolean to TRUE.  On MouseMove of the front panel, if the boolean is TRUE, fetch the TopRow property from the listbox.  On MouseUp on the front panel, set the Boolean to FALSE.
3. Use a picture control to create a scrollbar to your liking.  The picture control gives you excellent control and all the events you need, but you have to draw and manage everything yourself.

Good luck!

[S_Kanchap]

Thanks a lot for prompt reply !!!

I have solved it almostly.........

[Balaji_DP]

i have labview 8.21 , im going to  interface  with PLC.. is there required device drivers....?

i just using Data socket only from the option using front panel, and also i ll use datasocket vi...

i dont have DSC module....

reply me..

[MissyS]

Hi,

What PLC device do you want to communicate with? Depending on the device, you will likely have different options.

Are you able to get some communication working already with DataSocket?

Regards,

[Balaji_DP]

hi,

          we are using Allen Bradely - PLC(ABB). we already installed one system using ABB PLC with Labview version 7.0  with DSC Module and successcully running,

for the another system , where i used Datasocket VI's for sending signals to the PLC, for reading signals i am using on front panels controls--> right click to --> advance---> Data

socket, there i given an address of the PLC i/o's, this is also well communicate with the system.

my query is, if we going to communicate with PLC, is need to install the Device drivers for the any version of LabVIEW ? but im not going to use DSC module..

for the above projects im not used any device drivers...

Regards,

Balaji DP