Regarding to your screenshot, now it should be OK, you set all the 4 AO voltages to zero when you finish the while loop.
Express VIs: eliminate them! Use the same DAQmx programming as for the AO voltage channels. Your Express AI VI is configured as I see, to measure Voltage, Current, Voltage_0, and Current_0 channels. You read 10 samples with 10Hz rate, so your iteration speed will be about 1 second. This Express VI does already times your while loop, delete the "Wait (ms)" function from the while loop, which you set for 100 msec. It does not make sense in this case.
You can convert your DAQ Assistant Express VI into proper DAQmx code, and use it. Set the DAQmx Read for Nchan/Nsamples, you will get a 2D array which has 4 rows (your 4 input signals) and 10 columns (the 10 samples per channel). After this you can play with this 2D array, you can split it, etc... In this way you eliminate the "evil" dynamic data, and the need of the additional Express VIs.
Just feel free to post any new changes on your code, or your questions! This is the way to learn LabView 😉 Trial and error, and asking on the forum...
EDIT:
"I did this way at first but it also continuons send voltage after press stop button..."
Could you describe what this means? 🙂 If you press the stop button, the 4 AO voltage channel should be set zero. Check it with a multimeter, I do not know your actual HW config...
EDIT2: if you post your VI again, please set your HW channels to the physical channels which you actually use, and save them as default via the edit menu. After posting your VI we can see your HW channels. I see that, you use a cDAQ hardware for the analogue inputs. What HW do you use to generate the voltage outputs? On your front panel I see the same Dev1/ao0 default value for all the four AO physical ch controls...
