Terminal Servers
Terminal servers transform any serial device into an Ethernet-capable device that can be used in a network. These servers allow terminal devices such as a printer, control mechanisms or control systems to be used in a network without relying on the serial port of a computer for connectivity. This way, any terminal device can be connected to the network and the internet and accessed from anywhere. Terminal servers work by creating virtual serial ports which emulate physical serial ports and are used to connect the peripheral devices to the network. They assign TCP ports and IP addresses to facilitate communication between the users and the connected devices.
A terminal server can be a simple device that just connects the terminal device to the network without any security or authentication, or it can be a more complex device that offers options similar to routers and Ethernet switches. Devices with no authentication or security features are often used in small offices when connecting printers. This is usually a situation where data and access to terminal devices are not a security issue. More sophisticated terminal device servers with multiple authentication and full encryption are used in environments where security and safety are critical. This can include remotely operating factory control mechanisms or environmental control systems.
Industrial device servers are designed to operate reliably in harsh environmental conditions that may expose them to extreme temperatures, dirt, oil, and gas. They can also be certified for hazardous locations and typically offer enhanced surge protection.
Products
Ethernet hubs, switches and routers connect computers to networks, devices and other computers.
Ethernet hubs are the least intelligent of the three devices. They simply take any message that is received and transmits it to every other device connected to that hub. For example, if CPU 1 on a network wants to send a message to CPU 5, it will send that message through the hub.The hub will then take that message and send it out to every connected device on that hub regardless of the intended target. When CPU 5 receives that message and wants to respond, it will send its response through the hub which sends it to every connected device. Ethernet hubs do not manage any data that is sent and tend to bog down networks. They also do not offer much security for the network. For these reasons, Ethernet hubs are are being replaced with network switches.
Switches transmit data from one device to another on the same network. Unlike a hub, switches use a switch table to learn where data came from and where to send it. Switch tables store Mac addresses and device ports. By storing this data, a switch can operate more efficiently than a hub, greatly reducing the traffic within the network.
Routers transfer data between devices while learning the location of those devices within the network. They are also a junction between two or more networks. An example of this would be a home router where the home network is connected to the Internet. Another example would be when the router connects two or more networks with different business functions. In addition to connecting two or more networks, a router offers important security features that help protect the network.