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Power source 4130 current programming at 0 A

Hi,

 

I'm trying to develope an aplication with the power source PXI 4130 to produce pulses between 0 and 100mA (the duty cycle and the frequency may change).

 

 I copied mostly all the code from an example for this power source to generate waveforms with this power supply and it produces pulses betwen >0 and 100mA with no problem, but the subVI that writes the value of the output current fails when the value is just "0" (It says that the minimum value is 40e-3).

 

I know that is uncommon to want to put a value of 0 amperes to a power source, when you can try to switch it off or to disable its output; but disabling its output produces noisy results in the circuit.

 

 

I want to know if there is any code implementation or alternative to produce these pulses between just 0 and an arbitrary amplitude.

 

 

Thanks!

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The minumum allowable current setpoint is 2% of the current range that the PXI-4130 is set to.  If you switch to the 200mA range on the 4130 (instead of the 2A range) you will be able to program down to 4mA.  Is a current of 4mA close enough to 0 for the circuit you are working with?  If so, this is the easiest method.  Just set the "current limit autorange" propery to "true" immediately after you call the NI-DCPower Initialize funciton, and then use 4mA as your low value.

 

If 4mA isn't low enough, one option to get you closer to 0 current would be to change the current range on the PXI-4130 to the lowest range of 200uA during the low part of the pulses - that would give you the ability to program down to 4uA.  The fastest way to do this on the fly would be to call the "abort" VI, then change the range and current setpoint using a property node, then call the "initiate" VI.  How fast do you need the frequency of your pulses to be?  This may or may not be a viable solution based on how fast you are going. 

 

Another option to get all the way to 0 current would be to use an external relay on the output of the PXI-4130 - you could use the PXI-2503 switch to open or close the circuit as needed.  Again, this would affect your max attainable frequency because the 2503 can switch at a max of 200 cycles per second.

 

Do any of those options seem like they would work for you?

 

Have a great day!

Travis W

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