How to give SCPI commands to the multiple channels of a power supply simultaneously using VISA functions in labVIEW?

[divb]

I'm using a programmable DC power supply PSD7303A, and I want to operate all the channels of the power supply simultaneously and give separate SCPI commands through VISA in labVIEW to them. Semicolon method is not working.

For example, I want to use PID loop on 2 channels of Power supply separately and operate each one differently, but at the same time. First channel is connected to a heater trying to maintain the voltage at 3V while the other channel is connected to another heater trying to maintain voltage at 5V. So as clear from this example, they should be working continuously to regulate the voltage and simultaneously. So how to tackle with this multiple channel problem?

Any suggestions will be highly appreciated.

Thank you.

[GerdW]

Hi divb,

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@divb wrote:

I'm using a programmable DC power supply PSD7303A, and I want to operate all the channels of the power supply simultaneously and give separate SCPI commands through VISA in labVIEW to them. Semicolon method is not working.

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First step: read the fine manual of your device.

Then you should have learned about the capabilities of that specific device.

Does it even allow you to operate its several channels simultanously?

In case it does: HOW does it allow simultanous operations?

Once you answer those two questions you can implement the required steps in LabVIEW using the needed (SCPI) commands…

[Kyle97330]

"Semicolon method is not working."

Does that mean:

• "The device doesn't accept commands when I send them separated by semicolons", or
• "The device accepts semicolon-separated commands, but it's still not simultaneous enough for my needs"

?

If it's the first one, can you post what you're sending?

If it's the second one, then there is no way to send commands "more simultaneously" with SPCI natively.  You will have to find a way to synchronize your operations another way.  

[Frozen]

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@Kyle97330 wrote:

"Semicolon method is not working."

Does that mean:

• "The device doesn't accept commands when I send them separated by semicolons", or
• "The device accepts semicolon-separated commands, but it's still not simultaneous enough for my needs"

?

If it's the first one, can you post what you're sending?

If it's the second one, then there is no way to send commands "more simultaneously" with SPCI natively.  You will have to find a way to synchronize your operations another way.  

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The third possibility is:

• I have tried to implement the Semicolon command but have done it incorrectly and the instrument is reject the command.

In which case you need to go back to the manual and read up on the correct syntax of chaining commands together with a semicolon.

[divb]

Thank you everyone for your suggestions.

Since my problem is related to continuously changing voltage, so by semicolon method, it is switching between channel 1 and 2 very fast.( I'm afraid it can damage the power supply too). Is there any way how I can do it simultaneously? (Such that both the channels keep operating at the same time without switching)

PFA the code and a short video.

(Just to refer about the front panel graphs: I'm actually making PID loops. The temperature of the 2 heaters connected to both the channels of the power supply are trying to reach 40 degree Celsius, hence changing power supply voltage continuously by PID feeedback)

Any help or suggestions will be highly appreciated.

Thank you.

[RTSLVU]

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@divb wrote:

I'm using a programmable DC power supply PSD7303A, and I want to operate all the channels of the power supply simultaneously and give separate SCPI commands through VISA in labVIEW to them. Semicolon method is not working.

For example, I want to use PID loop on 2 channels of Power supply separately and operate each one differently, but at the same time. First channel is connected to a heater trying to maintain the voltage at 3V while the other channel is connected to another heater trying to maintain voltage at 5V. So as clear from this example, they should be working continuously to regulate the voltage and simultaneously. So how to tackle with this multiple channel problem?

Any suggestions will be highly appreciated.

Thank you.

---

I just took a quick skim of the manual and the SCPI command set is pretty small and straight forward. I see no details about chaining SCPI commands so it is possible that you will have to send the complete command separately for each channel.

Honestly you can only send any instrument one command at a time, you just have to do it fast enough that it appears simultaneous. 

[divb]

Thank you, but my power supply is showing lag while switching channels. It is not able to change values with the same speed as labVIEW is processing. Any idea on how I can increase the speed of channel switching in my power supply PSD7303A?

In case of very small rate like Rate=2, there is no lag, but  beyond it lag is increasing with rate.

[GerdW]

Hi divb,

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@divb wrote:

Any idea on how I can increase the speed of channel switching in my power supply PSD7303A?

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Read the manual of your powersupply. It will contain the needed information - otherwise ask the manufacturer…

[santo_13]

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@divb wrote:

Thank you, but my power supply is showing lag while switching channels. It is not able to change values with the same speed as labVIEW is processing. Any idea on how I can increase the speed of channel switching in my power supply PSD7303A?

In case of very small rate like Rate=2, there is no lag, but  beyond it lag is increasing with rate.

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It is possible that your power supply is not designed to be high performant across channel and simultaneous operations. Can you check with the manufacturer if that is even possible?

Worst case, you need to buy another power supply that can do stuff simultaneously at high speed.

[billko]

Depending on the instrument, it may be possible to operate on a list of channels.  You'll have to consult the manual to see if it is possible.