recording data

Good morning,
how can I register data on arduino. Do I need an external memory? which memory can I attach to arduino? I need to register for a maximum of about 24h and I can not leave a PC attached for 24 hours I would like to connect a memory card to download at the end of the cycle.

Thank you for any information.

Attach an SD card module and save the data to a SD card. At the end of the 24 hours, pull the card and read with PC.

To suggest an alternative to SD card we need to know:
What is the sample rate? How much data do you need to store? Which Arduino do you want to use?

By far the easiest way to log data from an Arduino is to use the SparkFun Openlog.

It is self contained, with a uSD card up to several Gb. To use it you simply connect it to an Arduino and print to a hardware or software serial port. I use them to log data for months at a time. Obey the 3.3V IO restriction, best to use a 3.3V Arduino.

Thank you to both.
The sample rate is each 10 second and record in real time.

I don't have decide wich arduino is better for me because I would like uderstand which has multiple input ports to connect multiple sensors to the same board, considering that each sensor has two signal wires. although I probably need to connect a multimeter between the sensor and the arduino ..

The SparkFun Openlog is programmable with software of arduino?

multiple input ports to connect multiple sensors

This page shows the different Arduino boards and shows the number of input (analog and digital) available on each.

each sensor has two signal wires

Does that mean a differential output (+ sig, - sig) or does that mean single sided (+ sig, ground)? If differential, there are Arduinos with differential analog inputs.

The SparkFun Openlog is programmable with software of arduino?

Yes, OpenLog is an Arduino. But you are extremely unlikely to need to reprogram it.

Thank you to both