Logic analysers are an incredibly valuable piece of test and measuring equipment, but sometimes it can be hard to work out exactly what you need, and what model is going to best suit your needs. If you’re not sure what a logic analyser is, then go and check out our tutorial What is a Logic Analyser for a run down.
Our favourite brand of logic analyser is Saleae. As far as features, value for money, and an all-product, they’re line up is pretty hard to beat. So today we’ll be comparing the different offerings from Saleae with some pointers on which one is going to be best for you.
Saleae Models
Saleae offer 4 versions of their popular logic analyser; the Logic 4, Logic 8, Logic 8 Pro, and Logic 16 Pro. The number in the name refers to the number of channels they have. One of the coolest things about Saleae is that all of these pins can record the digital and analogue signals on them at the same time! The exception is the Logic 4 which only has one combined A/D pin, the other three are digital only. The table below shows the key points of difference between the different models. Something to bear in mind is that the Logic 4 and 8 have USB 2.0, whilst the Logic 8 Pro and 16 Pro have USB 3.0. The need for USB is due to the bandwidth available on USB when recording with more than 8 channels.
So what is it exactly we should we be looking out for? Well it depends on what you want to do with it. Obviously you’ll be wanting to record digital signals with it, so the speed of the signals you want to record will determine whether you go between the 4, 8 or 8 Pro. Generally speaking, for capturing digital signals, the two most important things to look for is the maximum speed for digital signal it can capture, and the number of pins. For example, if you wanted to analyse a SPI bus which requires four pins, you would use up all the pins of the Logic 4. However the 8 or 8 Pro would give access to another SPI bus or say two more I2C busses.
Think of the Logic 4 as the entry level analyser; powerful, but with less features than its older brothers. The Logic 8 brings twice the amount of pins, and a huge bump in specs across the board, for less than $200 more. Then you step up to the Pro 8 model which have many times the sample rates, digital speeds, and also give a much wider range of analogue voltages it can capture. The only main difference between the Logic 8 Pro and Logic 16 Pro is the number of pins. They both feature a crazy 500Mhz digital signal range, can read logic levels from 1.2V-5.5V, and have +-10V analogue capturing. You then just need to decide on how many pins you want.
Our Recommendation
At the time of writing this article, I personally have a Saleae Logic 8. I decided that I definitely needed the 8 pins, and wanted to be able to view the analogue signals on all of them, and whilst the extra threshold of analogue inputs on the Pro line would’ve been nice, for view and analysing analogue waveforms, and oscilloscope is the better tool anyway. Plus the majority of low level digital communication protocols are easily measureable within the range that the Logic 8 offers. Plus for the cost of a Logic 8 Pro, I could buy 2 Logic 8’s. However if I did want the extra bandwidth and features available, I would definitely move on the Logic 16 Pro as it gives possibly the best bang-for-buck on any logic analyser on the market. Period.
Something else to keep in mind is that with your Saleae, whatever model you buy, you’re also getting a set of high quality probes, the amazing build quality that Saleae is known for, and the easiest to use, yet powerful Saleae software. Hopefully this gives you a bit of an idea on which Saleae model is best for you. We'd love to hear your opinions and/or experiences with the amazing Saleae gear, so comment below and get making!
