PicoScope 7 Software
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Struggling with memory concepts
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SteveThackery
- Newbie
- Posts: 1
- Joined: Sun Mar 01, 2020 2:01 pm
Struggling with memory concepts
Just ordered a 2204A and looking forward to it arriving.
I'm struggling with some basic concepts - specifically the relationships between the sample memory (8K in my case), the samples shown on the screen, and the samples that can be stored in my PC memory.
My PC screen is less than 8000 samples wide, so where are the samples I cannot see? Are they "outside" the left and right boundaries of the screen, or are they "between" the samples I can see, becoming visible when I zoom in?
Can I store more than 8K samples by storing them in the PC memory? Does the oscilloscope send the samples up to my PC continuously, or does it just send a "picture" to be displayed? When I store a captured waveform, am I storing all the data points, or just those that are actually visible on the screen?
You will see I have loads of questions! Rather than answering them all, is there an article that I could read which covers these basic concepts? I don't want to take up anyone's time - really I'm just looking for a pointer which will help me get started.
Thanks, all!
I'm struggling with some basic concepts - specifically the relationships between the sample memory (8K in my case), the samples shown on the screen, and the samples that can be stored in my PC memory.
My PC screen is less than 8000 samples wide, so where are the samples I cannot see? Are they "outside" the left and right boundaries of the screen, or are they "between" the samples I can see, becoming visible when I zoom in?
Can I store more than 8K samples by storing them in the PC memory? Does the oscilloscope send the samples up to my PC continuously, or does it just send a "picture" to be displayed? When I store a captured waveform, am I storing all the data points, or just those that are actually visible on the screen?
You will see I have loads of questions! Rather than answering them all, is there an article that I could read which covers these basic concepts? I don't want to take up anyone's time - really I'm just looking for a pointer which will help me get started.
Thanks, all!
Re: Struggling with memory concepts
Hi Steve,
First of all the best place to look for documented and video information is our Library here: https://www.picotech.com/library, and there is also a User Guide that you can read here: https://www.picotech.com/download/manuals/picoscope6-oscilloscope-software-users-guide.pdf. I'm not aware of a document explaining what you are asking (but there may well be as I don't continually check what information is available) so I'll explain this for you.
It's helpful to think of the 3 types of memory operation you're referring to as (a) 'Waveform Buffer' for each captured waveform (or just 'Waveform'), (b) 'Buffer Memory', and (c) 'Computer Memory', which is used as Application Transfer memory. In case you haven't already done so, it's also helpful if you enable the Properties Pane to be displayed in PicoScope 6 (you can do this by going to 'View->View Properties' in the Menu, which will open the Pane on the right of your display) as it will show a summary of the important parameters that you need to know in order to work out and understand what is going on.
Every time you perform a capture of a Waveform to display on your Computer monitor, a number of samples are collected (the number being displayed in the Properties). This number of samples is stored in the Waveform Buffer during capture. So, the Waveform Buffer size will be determined, in the software, by the number of samples to be stored in it. This software defined 'Waveform Buffer', in practice, is implemented as part of the hardware 'Buffer Memory' in the PicoScope Device.
If you are using a Single Trigger and you perform another capture, the new sample values will also be stored in the same software Waveform buffer, and in the same part of the hardware Sample Buffer over-writing the previous values. If you now change the Trigger Mode to Repeat Trigger, and then perform a capture, the old samples for the previous Waveform Buffer will again be overwritten, but you will also have 31 additional new waveforms that will each be stored consecutively in the (now larger) software Waveform Buffer, and in a larger section of the hardware Buffer Memory. So the hardware Buffer Memory will now have been split to hold 32 individual sets of waveform data, and you can scroll through the different waveforms that are stored in the software Waveform Buffer (and hardware Buffer Memory) by clicking on the 'Buffer Overview' icon (the icon that looks like a compass).
The number of waveforms captured can be changed (32 is the default) by going to 'Preferences' and changing the 'Maximum Waveforms' value under the 'Waveform buffer' section, however, you can only capture as many waveforms that will actually fit in your hardware Buffer Memory. If you change the Maximum Waveforms to 10,000 (the upper limit of how many can be captured) you may find that the actual number displayed will be less than 10,000, and this will therefore be the maximum number of waveforms that can be stored in the hardware Buffer Memory.
You will notice that if you change the Timebase (Time/div) value either the sample rate will change or the value for the number of samples to be captured will change. When the number of samples changes your waveforms will obviously be stored in a larger or smaller software Waveform Buffer. So, the maximum number of waveforms that can be stored in your hardware Buffer Memory will depend upon the size of the hardware Buffer Memory and the number of samples you will be using to capture a waveform. You can find the size of the hardware 'Buffer Memory', under the 'Horizontal' section of our specifications for the PicoScope.
While all of this is going on, the Waveform Buffer data in the hardware Buffer Memory is being transferred to the computer to be stored in the Computer Memory hardware. The Computer Memory hardware is typically much larger than the hardware Buffer Memory in the PicoScope, so the size of it is usually not significant (it's only significant if you're Streaming the data to the Computer using our Software Development Kit, which is one for you to read up on, if you're interested, once you're more familiar with the operation of the PicoScope and want to do more that the PicoScope 6 software enables you to do ).
Regards,
Gerry
First of all the best place to look for documented and video information is our Library here: https://www.picotech.com/library, and there is also a User Guide that you can read here: https://www.picotech.com/download/manuals/picoscope6-oscilloscope-software-users-guide.pdf. I'm not aware of a document explaining what you are asking (but there may well be as I don't continually check what information is available) so I'll explain this for you.
It's helpful to think of the 3 types of memory operation you're referring to as (a) 'Waveform Buffer' for each captured waveform (or just 'Waveform'), (b) 'Buffer Memory', and (c) 'Computer Memory', which is used as Application Transfer memory. In case you haven't already done so, it's also helpful if you enable the Properties Pane to be displayed in PicoScope 6 (you can do this by going to 'View->View Properties' in the Menu, which will open the Pane on the right of your display) as it will show a summary of the important parameters that you need to know in order to work out and understand what is going on.
Every time you perform a capture of a Waveform to display on your Computer monitor, a number of samples are collected (the number being displayed in the Properties). This number of samples is stored in the Waveform Buffer during capture. So, the Waveform Buffer size will be determined, in the software, by the number of samples to be stored in it. This software defined 'Waveform Buffer', in practice, is implemented as part of the hardware 'Buffer Memory' in the PicoScope Device.
If you are using a Single Trigger and you perform another capture, the new sample values will also be stored in the same software Waveform buffer, and in the same part of the hardware Sample Buffer over-writing the previous values. If you now change the Trigger Mode to Repeat Trigger, and then perform a capture, the old samples for the previous Waveform Buffer will again be overwritten, but you will also have 31 additional new waveforms that will each be stored consecutively in the (now larger) software Waveform Buffer, and in a larger section of the hardware Buffer Memory. So the hardware Buffer Memory will now have been split to hold 32 individual sets of waveform data, and you can scroll through the different waveforms that are stored in the software Waveform Buffer (and hardware Buffer Memory) by clicking on the 'Buffer Overview' icon (the icon that looks like a compass).
The number of waveforms captured can be changed (32 is the default) by going to 'Preferences' and changing the 'Maximum Waveforms' value under the 'Waveform buffer' section, however, you can only capture as many waveforms that will actually fit in your hardware Buffer Memory. If you change the Maximum Waveforms to 10,000 (the upper limit of how many can be captured) you may find that the actual number displayed will be less than 10,000, and this will therefore be the maximum number of waveforms that can be stored in the hardware Buffer Memory.
You will notice that if you change the Timebase (Time/div) value either the sample rate will change or the value for the number of samples to be captured will change. When the number of samples changes your waveforms will obviously be stored in a larger or smaller software Waveform Buffer. So, the maximum number of waveforms that can be stored in your hardware Buffer Memory will depend upon the size of the hardware Buffer Memory and the number of samples you will be using to capture a waveform. You can find the size of the hardware 'Buffer Memory', under the 'Horizontal' section of our specifications for the PicoScope.
While all of this is going on, the Waveform Buffer data in the hardware Buffer Memory is being transferred to the computer to be stored in the Computer Memory hardware. The Computer Memory hardware is typically much larger than the hardware Buffer Memory in the PicoScope, so the size of it is usually not significant (it's only significant if you're Streaming the data to the Computer using our Software Development Kit, which is one for you to read up on, if you're interested, once you're more familiar with the operation of the PicoScope and want to do more that the PicoScope 6 software enables you to do
).Regards,
Gerry
Gerry
Technical Specialist
Technical Specialist