Last value from a loop and values inside the loop

Question

Hi
Sorry about the confusing heading above, but its late at night and better words do not occur to me rightaway. Let me explain my situation.
I have a single instrument (a voltage source) that is being swept from one value to another for an experiment. It has three VI's : 1. enable o/p. 2. Set a voltage output level. 3. diable o/p.
I am using the error in and error out pins of instrument vis to properly sequence operations. I connect the error out pin of VI 1 to the error in pin of VI 2. Each of these errors is a cluster of three values.
When I try to wire the error out from VI 2 inside the loop to VI 3 outside the loop, the wiring breaks as I am then trying to connect an array (a 1 dimensional n member array of error outs) to a single error in pin. Trying to connect it to an array outside the loop is obviously the same. (I am making an assumption here - while the loop is running, I do not need to make certain of the sequencing of operations by putting a feedback node on VI 2 - that would mean something quite different in any case.).
So, how do I pass the last value (in this case, the error out cluster from the last stage) to error in pin of VI 3 ?
I have read that it might be possible using shift registers. I am quite new to LabVIEW. A somewhat detailed description of what I need to do would be nice.
Thanks.

Answer 1

Hello,
There are basically two options:
Handle the errors outside the for-loop
Handle the errors inside the for-loop
For you solution 1 is the easiest achievable, after the for loop use the 'Merge Errors' VI this will change the 1d-array into a cluster. The downside is that if an error occured later states of the loops don't know this
Solution 2 uses the shift register you mentioned. To use this you have to right-click on the right hand-side tunnel of the error wire (where it leaves the for-loop) and select shift register, sequentially your mouse pointer changes into an downpointed arrow, click on the entry tunnel on the left of the for-loop. What happens is that an error in the for loop is remembered into the next iteration (use execution highlighting to watch these)
Here is some code:
A good start might be:
The link to the LabVIEW Learning Center is here
Ton
Message Edited by TonP on 09-25-2006 08:01 AM
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