I need a data logging system where the operator can select 2 logging parameters: Log Period and Sample Time. I also need a START and STOP button to control the logging session. For example, set the log period for 1 hour and the sampling time for 1 second. (I may be using the wrong jargon here.) In this case when the START button is clicked, the system starts logging for 1 second. An hour later, it logs data for another second, and so on until the operator clicks the STOP button. (I will also include a time limit so the logging session will automatically stop after a certain amount of time has elapsed.)
It’s important that when the STOP button is clicked, that the system promptly stops logging. I cannot have the operator wait for up to an hour. Note that a logging session could last for several days. The application here involves a ship towing a barge at sea where they want to monitor and data log tow line tension. While the system is logging, I need the graph X-axis (autoscaled) to show the date and time. (I’m having trouble getting the graph to show the correct date and time.) For this application, I also need the system to promptly start data logging at a continuous high rate during alarm conditions. Of course I need to archive the data and retrieve it later for analysis. I think this part I can handle. Please make a recommendation for program control and provide sample code if you can. It’s the program control concepts that I think I mostly need help here. I also wish to use the Strip Chart Update Mode so the operator can easily view the entire logging session. DAQ Hardware: Not Selected Yet LabVIEW Version: 6.1 (Feel free to recommend a v7 solution because I need to soon get it anyway.) Operating System: Win 2000 In summary: How do I control a graphing (data log) session for both period and sample time? How do I stop the session without having to wait for the period to end? How do I automatically interrupt and control a session during alarm conditions? Does it make a difference if there is more than one graph (or chart) involved where there are variable sample rates? Thanks, Dave
