PORTABLE USB MODEM

4.AT Commands, S-Registers, and Result Codes

4.1AT Commands

AT commands are used to control the operation of your modem. They are so called because each command must be preceded by the characters AT to get the ATtention of the modem.

AT commands can be issued only when the modem is in command mode or online command mode. The modem is in command mode when it is not connected to another modem. The modem is in data mode when it is connected to another modem and ready to exchange data. Online command mode is a temporary state in which you can issue commands to the modem while connected to another modem. To put the modem into online command mode from data mode, you must issue an escape sequence (+++) followed immediately by the AT characters and the command (for example, +++ATH to hang up the modem). To return to data mode from online command mode, you must issue the command ATO.

To send AT commands to the modem you must use a communications program, such as the HyperTerminal applet in Windows NT® 4.0, or the communications program included with your modem. You can issue commands to the modem either directly (by typing them in the terminal window of the communications program) or indirectly (by configuring the operating system or communications program to send the commands automatically). Fortunately, communications programs make daily operation of modems effortless by hiding the commands from the user. Most users, therefore, need to use AT commands only when reconfiguring a modem (for example, to turn autoanswer on or off).

The format for entering an AT command is ATXn, where X is the command and n is the specific value for the command, sometimes called the command parameter. The value is always a number. If the value is zero, you can omit it from the command; thus, AT&W is equivalent to AT&W0. Most commands have a default value, which is the value that is set at the factory.

You must press ENTER to send the command to the modem. Any time the modem receives a command, it sends a response known as a result code. The most common result codes are OK, ERROR, and the CONNECT messages that the modem sends to the computer when it is connecting to another modem. For a table of valid result codes, see Section 4.3.

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Black Box MD403A user manual AT Commands, S-Registers, and Result Codes
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MD403A specifications

The Black Box MD403A is a powerful and versatile device widely recognized for its advanced technology and its ability to streamline data communication. Ideal for both personal and professional use, the MD403A is designed to cater to various environments, from small offices to larger enterprises.

One of the main features of the MD403A is its robust connectivity options. It supports multiple interfaces, including USB, HDMI, and Ethernet, allowing seamless integration with various devices such as computers, projectors, and IP networks. This flexibility makes it a popular choice for businesses that require reliable data transmission across different platforms.

The device is equipped with advanced signal processing capabilities that ensure high-quality data transfer. Utilizing cutting-edge technology, the MD403A minimizes signal loss, thereby enhancing performance and ensuring that the transmitted data remains intact. This feature is particularly crucial in scenarios where large amounts of data need to be transmitted quickly and without loss of quality.

Another significant characteristic of the Black Box MD403A is its user-friendly design. The interface is intuitive, making it easy for users of all technical abilities to navigate the system effortlessly. It typically comes with a straightforward setup process, minimizing downtime and allowing users to get up and running quickly.

The MD403A also boasts advanced security features. It employs multiple encryption protocols to safeguard sensitive information during transmission. With increased cybersecurity concerns, this feature is essential for businesses that handle confidential data, ensuring compliance with various regulatory requirements.

Additionally, the device supports various video resolutions, making it suitable for both standard and high-definition applications. This feature is particularly beneficial for users who want to deliver high-quality presentations or video content without compromising on clarity.

In terms of durability, the MD403A has a sturdy design that can withstand the rigors of daily use. Its compact form factor allows for easy portability, making it an ideal choice for professionals who are always on the move.

In summary, the Black Box MD403A combines advanced features, multiple connectivity options, robust security, and ease of use, making it an essential tool for modern communication needs. Its adaptability and performance make it a preferred choice for users seeking reliable data transfer solutions in diverse settings.
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