Hayes command set

Under AT command set is a set originally developed by the company Hayes Communications and the quasi standard that have become commands for configuring and parameterizing of modems. The characters " AT" stand for "attention" and must be sent before each command. By measuring the length of the individual bits the transmission speed of the interface is thereby automatically determined.

The first modem with this instruction set in 1981 sold under the name Smart modem 300.

A device that dominates the AT command set is also referred to as a Hayes - compatible. Some of these instruction set was implemented by the ITU -T in the recommendation V.25ter; it takes its name V.250. The use of the standard necessitates the use of device-specific drivers, modem unnecessary.

Under Windows 3.x comes to a native standard drivers of the operating system used, which controls the modem using the AT command set. However, 95 usually device-specific device drivers to be used for Windows, so a " Hayes compatibility " on Windows is no longer necessary and is therefore not implemented in some modems. This can make it difficult to use other operating systems or even exclude, unless a specific driver is available.

Classes

The AT command set is divided into four classes:

  • ATS2? returns the value of register 2
  • ATS2 = 6 has the register 2 value of 6 to
Hayes Microcomputer Products Windows 95 International Telecommunication Union
4334
de