for andrew

[AndrewAlford]

I can't open your vi I only have 7.1.1. You have to perform the min max an mean functions on the arrays output from the timed loop. If you want the loop to operate until the batteries are dead then instead of using the time elapsed function to end the loop you will have to wire a comparison to the current to the stop. Eg if current reads less than 1mA stop and output the elapsed time value to a tunnel on the loop (Disable the indexing, this way you will only get the last value from the last iteration of the loop.)

I do not have the meter you are using so I cannot test any of this code. Make sure you add any configuration for the meter before the loop, you will have to step through the VI to see if the meter value settles with longer waits.

[1231]

hi again,

here is my vi i converted to version 7. can you fix up the mean and max/min so they work? like you said, also i am not sure  about the comparison, basically i want to leave this run until the batterys die out, im measure specs for the board. power consumption etc.

i have no idea how long this will take, probably a day. 

when i have an idea on the performance, i could get the vi to stop when the battery drops to say .5volts etc?

i have alot of tests to do here....

many thanks

Eric

[1231]

actually, that vi i sent should have the mean power sent to the measurment as well.

i will plot them all on excel when the results are done, namely :

mean power vs time

power vs time

current vs time

i also need to know the max power and min power dissapation and the times they occur, over the duration of the test.

[AndrewAlford]

Ok, I'm am offering to help not write the solution for you that would cost you $$$ .

So that being said, from the VI you have sent me you are not using the timed loop so I will assume the one second reading time is no longer a criteria.

You don't seem to understand how arrays work, your vi is taking one reading and creating an array of one value, you then perform you calculations on that one reading. You need to create an array of all of your measurements before doing any calculations. Using shift registers and build array functions will acomplish this. Under find examples search for arrays to find code examples. If you want to improve the perfomance of this VI you must move the save file outside the loop.

If you need more help I would suggest breaking down your questions into smaller pieces, don't ask the forum to build the solution for you, many of the more experianced members don't have time for this. But they will give you sugestions on eg, how to build an array, although most will point you to the shipping examples found under the Help-> find Examples.. this is an excelent resource for basic functions of LabView.

For stopping the VI wire the Voltage measurement to a Less than function wire the other side of the Less than function to a constant of 0.5, the output goes to the loop stop criteria.

hope this helps you out.

[1231]

ok no worries,

why do you need to move the measurment vi outside? just wondering.

well, the vi at the moment takes samples of the current and voltage, so that will be sufficent i guess.  i had alot of trouble with volts and current, trying them inside, and outside of loops, but this method works. even if it sucks!

i will have a go at the arrays, will let you know how i get on!

regards

eric

[AndrewAlford]

File saving takes a lot of system resources and causes delays in software exicution. If you save large amounts of data at a time this could take several seconds. The only reason I stated this was because your orginal request was to take readings every second. If time no longer is an issue then you can save whenever you want.

Definately let me know how you make out, and if you have any further questions. I would post a new thread for any new questions as alot of the members don't look into messages with a lot of replies.

Good Luck

Message Edited by AndrewAlford on 02-16-2006 01:52 PM

[1231]

question!

how can i build an array so if i dont have any values ? (leaving this run for howeve long it takes to die), ?

i got an example ' extract numbers' can i use this.? it outputs numbers and strings from an input string.

i have double coming out of the multiplier so need to convert that to a string?

[AndrewAlford]

Use the number to string conversions in the functions menu Strings->String/Number Conversion.

[1231]

ok, i got numbers and strings sent from my power node. do i put the number(s) into an array like i had and get max, min values? or do i need something else?

[AndrewAlford]

Ok, look at the VI attached and run it to see how arrays are created. You will notice I have included what you did in your VI to show you what actually happens (It writes one value to the array and on each itteration it over writes it).

Let me know if this helps. VI is in 7.1.1