Sensors for Science Lessons

[dhicks]

Hello All,

 

I've just seen a request go past from the science teacher for some sensing equipment, specifically some LogIt Voyager units. Just searching for information about them, I came accross this post:

 

http://www.edugeek.net/forums/bett-2018/130486-science-equipment.html#post1114702

 

@pete - can I just check that, am I right in thinking you can just plug a sensor into a USB port and it'll start logging data like a keyboard? Does the software only work on client-side devices (Windows, MacOS X, Linux), or is there something newer and web-based available?

 

What happens when you plug two devices in?

[pete]

Yes, with the ones we have - uLog USB Sensors. I haven't tried the Voyager models, so it's worth giving them a call to check it's the same.

 

With ours:

 

If you plug two devices in (say a PH probe and a temperature sensor) it'll treat them as separate inputs.

 

If you plug two temperature sensors into the same computer it'll see them as distinct devices, but you'll have to warm one up in order to tell which is which.

 

Similar to having two keyboards plugged in - the computer can handle it, but I've never tested if there's an upper limit at N+1 keyboards.

[dhicks]

I haven't tried the Voyager models, so it's worth giving them a call to check it's the same.

 

I might have got a bit over-excited when I saw the "like a keyboard" bit - I imagined something like a cheap barcode scanner, where you can plug one into an available USB port and start scanning barcodes, with the device acting as a "fake" keyboard and sending data to the computer as if someone was sitting typing characters in. That would make it very easy to write something to read data from a sensor, there would be no specialised library needed, you could just use basic "read keyboard input" functions in whatever language you had to hand.

 

I phoned LogIt yesterday and had a very useful conversation with support (who, somewhat refreshingly for an educational IT company, actually know their stuff), who explained that just because the USB device is seen as a HID device it doesn't mean it acts as a keyboard. However, with a bit more research it turns out that Chrome actually has an API to read / write data from USB devices, the specific example given being "data logging devices in an educational setting": https://wicg.github.io/webusb/#app-edu-devices