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Please suggest a suitable Raspberry Pi for data logging

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Jester:
I want to put together a multichannel (6 channels max) data logger that will run for extended periods a month at a time collecting data from both GPIB and a couple of serial ports.

I have never used a Raspberry Pi. Assume my Raspberry knowledge == 0.

What minimum flavour of Pi would you recommend that will get the job done?

Thanks J

rstofer:
You might consider the Pi 4 Compute Module, it would be easy to integrate onto another PCB.  Otherwise a 4B will work just as well and I would buy the 8 GB version, not that it will be necessary.

The really nice way to do everything that needs doing is to use a Pi 400.  Add a monitor and mouse and you're ready to go.  I really like this platform.  Everything to do with a project is running on the project machine itself.

I assume you will be recording to a file on the microSD card and some other process is going to read the file and present the output.  You can add a printer to Ubuntu and print the data formatted by the program you write.  Or, you can send the stuff over a network connection to a NAS or whatever.

Ubuntu gives you a lot of power.

There is a problem, however.  There is only one accessible serial port.  There are devices that connect over USB to provide a serial port.  I used to use cable type converters.  There are also some more expensive hubs but I don't know if either of these work on Ubuntu.  You'll have to do some homework.  Take a Pi USB port, run it into a USB hub and use USB<->Serial cables to the devices.

https://www.amazon.com/s?k=usb+serial+cable

If everything else fails, use a compute module at every external device and network the whole project to the host Pi.  Berkeley Sockets is easy to use on Ubuntu.  Use the compute module to provide a single serial port and grab the data for transmission over TCP/IP.  I would probably start with this approach because it leads toward future proofing.  Only the host code needs to change if I need to add 1 or 100 additional devices.  Distance doesn't matter, I can record data from anywhere with an internet connection.

mawyatt:
We've been using RPi for some time now as the main computer platform in various systems, ranging from single axis custom focus stacking optical system, to 4 axis stack & stitch focus stacking systems, and lately to a complex controller that is sort of a 15 bit 180VPP capable 128 independent channel AWG with Bi-Phase and Offset modulation capability. Even use the RPi as the overall system clock generator.

These RPi ranged from 3, 4, 400 and even Zero, although the Zero is somewhat slow. Agree having everything to do with the project running on the project machine itself, so everything is self contained is a really good approach and why we selected this method. With the built in Wireless, you can use VNC and operate from anywhere if desired.

Here's a couple images of the 64 channel system under test with RPi 400 and Zero.

Best, 

mawyatt:
Here's some links to systems built around the RPi, these are for optical focus stacking, but may be of interest.

https://www.photomacrography.net/forum/viewtopic.php?f=25&t=39756&hilit=Quad+Axis+Controller

https://www.photomacrography.net/forum/viewtopic.php?f=25&t=42140&hilit=Stack+Stitch

https://www.photomacrography.net/forum/viewtopic.php?f=25&t=38512&hilit=Focus+Stacking+Raspberry+Pi

Best,

Lindley:
Does it have to be a Rasp Pi ?

Depending on you needs you might find the humble Arduino or ESP32 module with an SD card are well able to do that data collection and in some ways easier to get going, eg No Linux
Heres just one of many such examples on the web, some even giving details of how to transfer to data to Excel etc.

https://maker.pro/arduino/tutorial/how-to-make-an-arduino-sd-card-data-logger-for-temperature-sensor-data

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