Logic Analyzer Frequently Asked Questions

The GoLogic7 software supports only one logic analyzer per computer. Up to 8 “copies” of the program can run together, but only the first copy has access to the logic analyzer device. The other copies always use demo mode.

Base memory option

• 72-channels; 67M samples; about 9 seconds
• 36-channels; 134M samples: about 12 seconds
• 18-channels; 268M samples: about 15 seconds
• 9-channels; 536M samples: about 15 seconds

Mid memory option

• 72-channels; 67M samples; about 19 seconds
• 36-channels; 134M samples: about 23 seconds
• 18-channels; 268M samples: about 30 seconds
• 9-channels; 536M samples: about 30 seconds

Large memory option

• 72-channels; 134M samples: about 36 seconds
• 36-channels; 268M samples: about 45 seconds
• 18-channels; 536M samples: about 60 seconds
• 9-channels; 1 billion samples: about 60 seconds

The above download times are provided for illustration purposes and not guaranteed. The download speeds on your PC may be slightly slower or faster. Transfers rates depend somewhat on the USB host hardware and kernel drivers.

As the trace size is reduced, the download time is also reduced. For example, trace captures with 8M samples or less download almost instantly.

A USB 1.1 host port downloads the data approximately 20X slower than the above values. Obviously, we recommend using a USB 2.0 host port.

After each download, the software must process the data. The post-download processing period is not reflected in the above USB download times. The one-time processing improves the real-time display speeds and allows the software to display hundreds of millions of trace samples in the WaveForm window. For traces 8M samples and smaller, this processing period is barely noticeable. But for very large trace captures, the one-time processing period make last several seconds.

NCI does not support streaming to PC memory or disk. USB "streaming" logic analyzers offer slower sampling rates across few channels. The Logic Analyzer Streaming topic discusses why NCI logic analyzers do not stream data directly to disk.

Time spanned = (Max samples) X (Time per sample)

Base memory option

•  72 channels: 34M samples @ 500 MHz = 67 milliseconds
•  36 channels: 67M samples @ 1 GHz = 67 milliseconds
• 18 channels: 134M samples @ 2 GHz = 67 milliseconds
• 9 channels: 268M samples @ 4 GHz = 67 milliseconds

Mid memory option

• 72 channels: 67M samples @ 500 MHz = 134 milliseconds
• 36 channels: 134M samples @ 1 GHz = 134 milliseconds
• 18 channels: 268M samples @ 2 GHz = 134 milliseconds
• 9 channels: 536M samples @ 4 GHz = 134 milliseconds

Large memory option

• 72 channels: 134M samples @ 500 MHz = 268 milliseconds
• 36 channels: 268M samples @ 1 GHz = 268 milliseconds
• 18 channels: 536M samples @ 2 GHz = 268 milliseconds
• 9 channels: 1 billion samples @ 4 GHz = 268 milliseconds

Of course, slower sampling rates increase the time spanned by a trace capture. For example, 1 billion samples using a 1 GHz sampling rate spans about 1 second. Likewise, almost 2 hours are spanned by 67M samples using a 10KHz sampling rate.

The timed spanned by Transitional timing mode depends on the input signal activity. If the input signals constantly change, the time spanned by a Transitional timing capture is about 1.5 to 2 times longer than if Normal timing at the same sampling rate had been used. If the inputs signals are slow relative to the sampling rate, or the inputs are inactive for long periods of time between bursts of activity, then Transitional timing is a huge improvement over Normal timing mode. The online manual’s Appendices explains the time stamp limits.

Yes! To accurately capture the input signals, both Normal and Transitional timing modes must over-sample your signals at least 5x. For example, the sampling rate should be at least 500 MHz to capture an accurate representation of a 100 MHz input signal.

Normal timing mode stores all samples to memory, even when the signals have not changed. Transitional timing mode stores only when a change occurs on the input signals. Given an identical 5x over-sampling for both modes, Transitional timing ignores 3 or 4 non-changing samples that Normal timing would store to memory. This extends the time spanned by a Transitional timing capture about 3 to 4 times greater than a Normal timing capture.

Of course, Transitional timing mode must also store a 32-bit timestamp with each sample. This timestamp memory reduces the sample depth by half. If the logic analyzer captures 134M samples in Normal timing, then only 67M samples are stored in Transitional timing mode.

But even with half the total samples, Transitional timing still captures a larger time-span than Normal Timing mode. Since Normal timing stores 3 to 4 redundant samples, Transitional timing usually captures from 50% to 100% larger time span.