Com ports

I was wondering how many arduino mega’s could be connected to 1 pc (with windows vista or 7)

regards,
Henk.

(127 * Number of USB Host Controllers) - Number of USB Devices

Or, 256 if Microsoft never changed this... http://support.microsoft.com/kb/100111

yeah people ask this question quite a bit. Each extra arduino you add in comes up as a seperate USB serial port so you can have as many as you could USB devices. The arduino IDE COM port list should just expand to as many as you have.

You would run out of power if you had too many though. A few powered USB hubs would be required.

Mowcius

A computer with 256+ Arduinos.... that would be one hell of a project.

ok, thanks for the answers!

so, the amount of com ports isn’t restrictive, when connecting say 40 arduino’s I get com4 - com43?

when connecting say 40 arduino's I get com4 - com43?

It depends on what else has been connected to the computer. You may get "holes" in the sequence. I believe the driver allows you to override the assigned port. If that's true, you can change the assignments so the ports are sequential.

The only caveat is the way ports above 9 are accessed. Ports 0 through 9 can be accessed using the simple DOS name "COMx" where "x" is the port number. Ports above 9 can only be accessed using the full NT device name "\.\COMx" where "x" is the port number. Because of the difference, some software does not support ports above COM9.

I write my own software to talk to the arduino's, it should be nice when my software also detects when a new device is plugged in (I create my C++ programs with RAD Studio 2010 from Embarcadero) and then also detect the special function of every arduino (but that quite easy, by sending a kind of code)

Because of the difference, some software does not support ports above COM9.

The arduino IDE seems to accept all COM ports though as I did set my arduino to COM256 for a bit of fun :)

You have an interesting definition of the word "fun". ;)

You have an interesting definition of the word “fun”.

Haha yeah well most people think that my idea of electronics as fun is weird. We all need little things to make life more interesting and using COM256 was one of those little things :slight_smile:

Mowcius

You would run out of power if you had too many though. A few powered USB hubs would be required.

What about to give the arduinos all extern power? 256*9V. Only if you had a power plant at home.

256*400mA 102.8A Max so a big supply would do fine.

Mowcius

400MAh

??? that's not a current.

do you mean 400mA, if so an arduino only needs about 50mA plus whet ever load is supplied to sensors and indicators. so lets say 250 mA, that's only 64A. :)

Who said 400MAh? :P

Yeah, the arduino duemilanove is 400mA max through the regalator isn't it so a max of 102.8A

Shouldn't be too bad but you would need a lot of powered USB hubs for plugging them into the PC!

Mowcius