How many com ports can there be?

Rayman

I just connected a FTDI chip and the Prop tool identified it as COM17 !
Is there any limit?

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My Prop Info&Apps: ·http://www.rayslogic.com/propeller/propeller.htm

CounterRotatingProps

It's probably 256

certainly a multiple of 2, so maybe it's

2³²



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Phil Pilgrim (PhiPi)

The highest is COM256, according to the Device Manager. Incidentally, the FTDI chips pose a real problem for production testing of boards that use them, since each has a different serial number and is assigned a different COM port number by Windows. You really have to jump through hoops to get com ports assigned by USB connector rather than by slave device ID.

-Phil

Rayman

It is a dilemma... At first, I was going to fix the serial# of all my FTDI chips... But, then I thought against it. Now, maybe I'll think about that some more...



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My Prop Info&Apps: ·http://www.rayslogic.com/propeller/propeller.htm

Post Edited (Rayman) : 6/20/2009 2:02:59 AM GMT

Phil Pilgrim (PhiPi)

When the MoboStamp-pe, which uses an FT232R, first went into production, I was faced with a real dilemma about how to set up the test program. Once I realized how difficult it was to override the serial number thing, I decided that, rather than trying to explain it, it would be easier just to buy a second-hand PC, configure it myself, and have the whole thing shipped to the factory.

-Phil

BADHABIT

Smart Phil.

I would recommend against that Ray. If one party buys multiples of the same item and hooks them up simultaneously it may cause conflict.
If that is not an issue, then it may be a good idea.

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BH

localroger

An interesting side note to this -- at work I have a PC with one regular COM port, one unused modem, and a 16-port Comtrol Rocketport PCI serial expansion card. (I use lots of serial ports.) The normal COM port is COM1; the unused modem is COM2, and the Rocketports are COM3 through COM18.

When I plug a Demoboard into the USB, it shows up as COM19. But when I plug in a PropPlug to program a Protoboard, it seizes COM3, disabling the Rocketport's COM3 until the PC is rebooted even if I later unplug the PropPlug. Weird.

Sapieha

Hi localroger.

It is posible You on first time You pluged PropPlug have not Rocketport card/PCB initialised.
You can reorder PropPlug in Win XP to have another COMxx number and then restart PC with Rocetport and PropPlug on line.
Then next time you unplug it and plug it other it will have new port number.

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Nothing is impossible, there are only different degrees of difficulty.
For every stupid question there is at least one intelligent answer.
Don't guess - ask instead.
If you don't ask you won't know.
If your gonna construct something, make it·as simple as·possible yet as versatile as posible.


Sapieha

localroger

@Sapieha -- I know the Rocketport was initialized because I've been using it for four years. It's not a USB device; it's a PCI card installed inside the computer, so it's always there. The first time I booted after installing it XP found the drivers (even though Rocketports aren't standard the drivers are included with XP) and installed the 16 ports, just as if it were a normal serial card. The ports are always there; if I open hyperterminal and tell it to start a connection on com16, there aer no balloon notices about finding the port. It's just there.

There is some difference in the USB drivers for the demoboard and propplug, which prevents the propplug from seeing that the rocketport is installed and allowing it to seize the API interface for com3. (Interestingly, the rocketport drivers continue to know that the com3 hardware exists through the diagnostic software which bypasses Windows, but the Windows API com3 calls are routed to the propplug driver instead of the rocketport driver).

I have also noticed that if the propplug is plugged into the PC when it boots up, it doesn't get detected; you must unplug it and plug it in after Windows has booted to get Windows to detect it. Again, my demoboard doesn't do this; it stays plugged into my other computer all the time, and usually just works.

What mystifies me about this is that I was under the impression that the onboard USB and propplug were essentially the same technology.

Sapieha

Hi localroger.

Have You tested to reorganize propPlug in Control Panel/System/Hardware/Devices-Ports on XP to have COMxx (COM20 maybe) but to that PropPlug must be active.
Then next time You plug PropPlug it will have that port number

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Nothing is impossible, there are only different degrees of difficulty.
For every stupid question there is at least one intelligent answer.
Don't guess - ask instead.
If you don't ask you won't know.
If your gonna construct something, make it·as simple as·possible yet as versatile as posible.


Sapieha

Ariba

What happens, if you have several FT232 chips with the same SerialNumber connected to a Windows PC?
Do you get another COM port number for every device? Or an error message?

Andy

Sapieha

Hi Ariba ....

Newer tested that.
But it can be problem in XP enumerator.
FT2XXX series chip with parallel interface with programing EEprom can be reprogramed to have another Serial/ID number.
But on FT232 I have not tested that posiblites yet.
Them have on this www. --- site one special program to reprogram FT chip's Serial/ID number.
You can test this

Regards
Christoffer

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Nothing is impossible, there are only different degrees of difficulty.
For every stupid question there is at least one intelligent answer.
Don't guess - ask instead.
If you don't ask you won't know.
If your gonna construct something, make it·as simple as·possible yet as versatile as posible.


Sapieha

localroger

@Sapieha -- I haven't tried that (didn't know it was possible) but I will on Monday.