Is there a function for delay?

[cloudies]

We used Labview to control the current injecting into the resistor and using Keithley multimeter (2000) to measure the voltage across the resistor. We would like to detect the voltage across the resistor after we've injected the current, however the program that we've written can't measure the correct voltage across the resistor. We are thinking of delaying the measurement of the voltage across the resistor so that it will only measure the voltage after a current is passed. What can we do to our existing program to accommodate this function?

[mikeporter]

I guess I am unclear on what you are trying to do. Are you needing the voltage drop across the resistor for some reason, or do you (as your code says) need the resistance of the resistor? By definition, unless there is another resistance in series with the one you are measuring, the voltage drop across the resistor will be equal to the source voltage.

If what you really need is the value of the resistance, simply put the meter into 4-wire measurement mode, coonect the leads and measure away. By the way, 4-wire mode is a way of improving the accuracy of the resistance measurement by effectively nulling-out the effect of the measurement lead resistances. The way it works is by using two wires on each side of the resistance. One wire on each end is connected to
a fixed current source. The other wires at each end are connected to a measurement circuit with a very high input impedance. These leads measure the voltage across the resistor right at the resistance. Because, the instrument now knows the voltage across the resistance under test and the current it is applying, determining the resistance is a simple math exercise (R=E/I).

What's more, because the input impedance of the voltage meaasurement is very high, the current flow through these sense wires is very low, which results is a very small voltage drop across the wires (E=I*R), which results in a very accurate measurement.

But again, could you please describe in a little more detail exactly what it is that you are trying to do?

Mike...

[Dennis_Knutson]

Even though you didn't include any of the Keithley VI's in your attachment, it's pretty clear that you've missed the concept of dataflow in LabVIEW. Because you have no data dependency between the voltage and current read VI's, they will execute in parallel and sometimes you'll get a voltage reading before the current is applied. To force the voltage reading to be done after, connect the last error out cluster of the current VI to the first voltage VI. Also, what's the point of the compound arithmetic function? If converts your resistance value to an integer.