how and what is best communication protocol between multiple micro-controller to one micro-controller(multiple slave to one master)

[RShar.9]

in that communication i have length issue (2 meter communication) , communication should be fast, less wire

[RShar.9]

so what will be efficient method to communicate to all 24 devices and get data from sd-card.

i did not get any practical answer.

[RShar.9]

can i use CAN protocol to communicate to all devices

what is the speed of CAN communication

[RShar.9]

In parallel communication we need clock or not?

[RShar.9]

can we use parallel communication for data transmission