Last value from a loop and values inside the loop

[m-s]

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.

[TCPlomp]

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

[TiTou]

Hello,
Just to add to TonP's help, see this and feel free to ask more question if I'm not clear.



Hope this helps 😉

Message Edité par TiTou le 09-25-2006 07:50 AM

[m-s]

Hello,

Thanks for the suggestions ! Using the shift register gets rid of the broken wires. I have not tested the application yet. Will get back to you when I do.