two HP e3631a DC Power timed switch

[jetfire]

Hi,

i try to use two DC Power supply  HP e3631a for timed Switching  with funktion like this：

DC Power Supply #1 on,enable only one channel with output 3.5 V ,DC Power Supply #2 all output off ,and runing VI for 30s,then

DC Power Supply #2 on,enable three  output 1V ,+18v，-18v,     DC Power Supply #1 channel off, runing VI for 20s,further periodically running like this....

i want to using timed swtiching case  structure for controlling this   periodically implement,but results is wrong because it doesn‘t  switch exactly after 30s or 20s,here i post my code,if f anyone can give me some ideas that would be appreciated.

Note：Labview 2009 Sp1

[crossrulz]

How close to the 30s and 20s are you getting?

You only need to set the supplies when you are switching cases.  There's no need to set them every iteration of your loop.  The communications takes time.  That could be throwing you off a little bit.  I don't have the drivers, but there could be some waits in them to allow for settling.

[jetfire]

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@crossrulz wrote:

How close to the 30s and 20s are you getting?

You only need to set the supplies when you are switching cases.  There's no need to set them every iteration of your loop.  The communications takes time.  That could be throwing you off a little bit.  I don't have the drivers, but there could be some waits in them to allow for settling.

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thank you for your reply,but i don’t understand what is“ set the supplies when you are switching cases”，can you give me some details？

[crossrulz]

When you switch from Case 1 to Case 2 or Case 2 to Case 1, that is the only time you need to set the supplies.  The rest of the iterations you can just read the measurements.  You know when you change cases by the Time Elapsed boolean.  So put your subVIs that setup the supplies into a case structure.

[jetfire]

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@crossrulz wrote:

When you switch from Case 1 to Case 2 or Case 2 to Case 1, that is the only time you need to set the supplies.  The rest of the iterations you can just read the measurements.  You know when you change cases by the Time Elapsed boolean.  So put your subVIs that setup the supplies into a case structure.

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thanks for explain in detail,i have another question：why doesn‘t waveform chart correctly display  elapsed time with case switching ？

[Dennis_Knutson]

There is no reason for it to display an accurate elapsed time. In order for a chart to reflect actual time when you just pass it a scalar, you have to set the offset and multiplier. The offset is the actual start time and the multiplier is the loop time. Look at the shipping example called Real Time Chart.

[jetfire]

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@Dennis_Knutson wrote:

There is no reason for it to display an accurate elapsed time. In order for a chart to reflect actual time when you just pass it a scalar, you have to set the offset and multiplier. The offset is the actual start time and the multiplier is the loop time. Look at the shipping example called Real Time Chart.

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hi,i have another question ： i am trying  to switching between DC Power without same period,und with Array Controller in Attachment i  want to switch between  different period,for example case1→run 20s→case2→run10s→case1→run15s→case2→run20s→case1.....Array Controller have all Switching time, How to complete this function？

thanks in Advanced.