ACM MODEMS

5/29/2004

Abstract Control Model (ACM). Abstract Control Model is a generic term used from time to time in a variety of (mostly academic) contexts. But a very high percentage of the usage refers to a specific technology used with USB modems. The ACM permits (requires) software to access USB modems using the "Hayes" (AT) command set. There are other access models that USB modems can use as well as or instead of ACM.

ACM Serial Emulation is an extension to the ACM. ACM Serial Emulation not only uses AT commands to control the modem, it also emulates some of the operations that software might perform on UART registers controlling a serial modem. USB modems that support ACM access behave much like serial modems and are generally usable in both Windows and Linux.

For more information on ACM and other models than most people would desire, see:

https://web.archive.org/web/20051101235558/http://www.usb.org/developers/devclass_docs/usbcdc11.pdf

(Google cache:) http://216.239.39.104/search?q=cache:jJP_AshK4pYJ:www.usb.org/developers/devclass_docs/usbcdc11.pdf+cdc+acm&hl=en&ie=UTF-

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