Hi, I have been working on a large project for several months and I am at the final stage of the project. However, when I want to use my program it gives me several problems. Let me first elaborate what the main progam does: The machine it operates has 5 sensors, and 4 motors The main program consists of 8 while loops: [DAQ loop] acquires 5 sensor voltages -> filters these (sample compression - mean) -> puts them in a queue that is accessed by the second loop [Visualization loop] dequeues measurement data from the first loop -> does some calculations and shows them in different sets of graphs (located in different tabs of the front panel) -> puts the original measurement data in a second queue for the third loop. [Calculation/storage loop] dequeues data from the second loop and stores the desired calculated values in a txt file [Motor Control loop] controls one motor. It listens to the 'Communication channel' (notifier between two motor control loops). If it receives 'Start motor', it starts (or continues) the internal case structures. If it receives the 'Stop motor' command, then the motor ceases all activities. It listens to the 'Mean gap' channel (notification from the DAQ loop with a mean value) to get the latest mean gap. If it matches the desired gap height, the loop continous with an iteration through the different shear rates. If it doesn't match, it sends a command to the second motor loop to 'Go to gap = xx.xx' (over the 'Communication channel'). In the latter case it subsequently waits again for a new 'Start motor' command. [Picomotor Control loop] controls the second motor. It listens to the 'Communication channel'. If it receives 'Go to gap = xx.xx' (with x a float), it reads out that floating number as a new target gap and puts it into a shift register. If it receives the 'Stop motor' command, then the picomotor ceases all activities. It listens to the 'Mean gap' channel to get the latest mean gap. As soon as this value is stabilized the picomotor loop will enter into the case structures. The difference between the target gap and the mean gap is used to calculate a step size for the picomotor. As soon as this step is zero, the picomotor loop sends a notification to the 'Communication channel' to 'Start motor'. It also listens to the 'Stop command' channel for a stop command. Loops 6/7/8 are event listener loops Now in short what do I do: I start a measurement, the gap height is adjusted to be the desired gap, then the first motor moves over a certain trajectory and then everything stops. The whole time, the DAQ loop is acquiring data and that data is visualized and calculated accordingly. Problem: I start the measurement, the gap is adjusted to the desired gap and then the first motor starts. It starts to move and then suddenly the program pauses for a few seconds (the motor can in the meanwhile continue to it's latest destination). After this pause, the program continues normally until a certain moment where it does the same thing. Just halts for a few seconds and then continues. This is really feaking me out because I cannot seem to figure out where the problem is located. Discarded explanation: queues getting full and the program having to wait for a dequeue operation: this was my first guess, but I included a check before each enqueue action to check whether the queue is full or not. If it is full then the oldest element will be discarded It would be super if someone has experienced anything like this before and could shed some light on this problem. If anything is unclear, just ask! I am using LabVIEW 8.5 on Windows XP. Thx, Giovanni

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Hi,

I I solved my problem with a combined solution from all of you. Instead of doing one query in the DAQ loop and the other in the motor control loop, I do both queries (one after the other) in the DAQ loop. Then I send the Motion done status over a notifier to the motor control loop which continuously reads the notifier. This way no conflict arises.

Thx for your help guys, I really appreciate it 🙂

Giovanni Vleminckx
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Using LabVIEW 8.5 on Windows7

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