What Is a Device Server?
A device server enables the connection of non-networkable devices to a network via serial interfaces or USB ports. This is essential for devices like older printers and scanners, which use RS-232C or USB connections and cannot directly connect to a network due to differing communication protocols. A device server acts as a bridge, converting these protocols to enable network connectivity.
This connectivity allows a single device to be accessible from multiple PCs, enhancing usability and flexibility.
Uses of Device Servers
Device servers are pivotal in networking devices that lack inherent network capabilities. By doing so, equipment such as legacy printers and scanners become accessible from multiple computers. Additionally, device servers facilitate the remote operation of computers via peripherals like keyboards and mice, overcoming the limitations imposed by physical proximity and cable length. Some device servers also support Internet connectivity, enabling the creation of large-scale systems and remote monitoring.
Principle of Device Servers
Device servers convert the communication method of serial devices to be compatible with Ethernet interfaces. This conversion can occur in three modes:
1. Real Com Mode
Creates a virtual COM port on the host computer, enabling data transfer and operational control through serial port line signals.
2. Socket Mode
Facilitates access to serial device servers on a TCP/IP network via standard sockets API, eliminating the need for additional drivers.
3. Port Sharing Mode
Allows multiple host computers to share a single device server’s port, enabling them to receive data from the same serial device concurrently.
Types of Device Servers
The choice of device server depends on the specific networking needs of USB or serial devices:
1. Embedded Device Server
These compact servers are integrated into devices, offering basic networking capabilities for small devices.
2. Serial Device Server
Suitable for networking devices with serial interfaces, often used in industrial settings for data collection and device control.
3. USB Device Server
Enables networking of USB devices within a small network, supporting high-speed data transfer for applications like USB audio and web cameras.
4. Internet Device Server
These servers support Internet connectivity for remote monitoring and management systems, offering a cost-effective solution without the need for dedicated lines.