What is a zero modem?

and null is a cable or adapter that allows communication of two serial devices without a modem. Some zero modems connect only data lines between devices, while others also include handharing signals. Engineers or technicians often use zero modems to communicate with devices that do not have a built -in console. These include many types of built -in systems, network switches and servers. They are also often used to tune operating systems if no keyboards or video services are available. The data transfer signal at one end of the cable is connected to the pin-data-data on the other and vice versa. This cross connection can also be implemented in the zero modem adapter. In this case, the standard serial cable connects one device with an adapter. The identical cable connects the adapter with the second device and the crossover is connected to the adapter -on. The line of one device on the dive can be connected to the Clear-to-Send line and vice versa. Depending on hardware and softwareOn both sides of the connection, this may be enough to continue communication.

Three other hardware handshaking signals can be implemented in zero modem. Some serial devices require that signals ready for data terminal, data and detection detects. When all three of these signals are applied, each device recognizes that the other is powered and connected. Many zero modems wire data-terminal terminal at one end to detecting carrier and on the other prepared data. However, some zero modems may not connect the detecting carrier signal.

Before developing a universal serial bus (USB), zero modem is timely used to share files between two computers. Between these two systems, a direct cable connection was created using their serial ports and zero modum. File transfer software designed for a link modem was then used to copy filesfrom one system to another. This was particularly useful for very large files that would not fit on a floppy disk or other removable storage media. For the same reason, direct connection was commonly used to transmit a large number of files in one batch.

Common modern use is access to the core of the operating system (OS) or a device without a bracket with a separate computer. Standard keyboard and display can often not be used when tuning the axis core or diagnosing core panic. NULL MOD can provide an engineer control over the system during the tuning session. Many devices are designed to work without a console such as network switches, Blade servers and embedded systems. If the keyboard and display or maintenance are temporarily needed for diagnosis, zero modem is a common means of access.