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Technical Reference

The following list contains further information about concepts that you may encounter when setting up and using your WebPorts.

Concept Information
Analog-to-digital converter (ADC) Analog-to-digital converter. An analog-to-digital converts a continuous input such as voltage to binary, time-sampled values.
Advanced RISC (Reduced Instruction Set Computer) Machine (ARM) Advanced RISC Machine. This type of processor provides processing power for custom application-specific integrated circuits and uses very little electrical power. The processors are used in mobile phones, GPS navigation devices, and game devices, and digital cameras, and many other applications.
Application service provider (ASP) Application service provider. Software that is provided over a network as a service to businesses that do not wish to, or cannot afford to, provide the software services for themselves.
API Application Programmer Interface. Software that provides source code specifications intended for use by developers to create interfaces that communicate with each other using the code routines, data structures, and object classes that may be provided by the API.
APN Access point name. Computer protocol that enables a user to access data over the Internet using a mobile phone network.
CPU Central Processing Unit. Carries out the instructions provided by a computer program. Normally these are basic logical, input/output, and arithmetical operations that form the basis of most software operations on a computer.
DAC Digital-to-analog converter. A device that converts a binary (digital) code to a continuous signal such as current, voltage, or an electric charge.
DoS Denial of Service. A common attack involving overwhelming a server with invalid requests.
Domain Name Server (DNS) This is the value that is associated with the Domain Name Server that your system interacts with on the Internet. Domain name servers convert text names that are easy to remember (google.com, spectrumcontrols.com) to IP address values. If you are going to communicate using the optional cell phone modem in data mode, you need to add a public domain name server address as the alternate DNS address when setting up your LAN. When in data mode, the cell phone modem uses the public DNS address to communicate via the Internet.
Dynamic Host Configuration Protocol (DHCP) A type of network configuration for host devices that dynamically provides IP, gateway, and routing address for devices that are connected to that network. This means that the WebPort dynamically allocates IP addresses to the devices that you connect to it. For example, when you connect a personal computer, programmable logic controller, or EtherNet/IP device to a LAN port on the WebPort, the WebPort senses the device is present and dynamically allocates the information that is needed to allow communications between the two devices. The WebPort assigns an IP address, a subnet mask address, and a gateway address to the new device from the range of addresses stored on the WebPort. The WebPort also provides a lease that defines how long these addresses are valid. This allows communications between the WebPort and the device. When the lease is up, if the device is still in use, the WebPort allocates addresses again. If the device is no longer in use, the address becomes available to be allocated to other devices.
DHCP Client Dynamic Host Configuration Protocol Client. When you connect a new device such as a computer, or a WebPort to a network that has a DHCP Server set up, the client device gets its IP address and other configuration information such as default gateway and domain name from a group of IP addresses maintained by the DHCP server for a defined time period.
Flash A type of non-volatile memory that can be electronically erased and re-written.
FTP/FTPS File Transfer Protocol/Secure File Transfer Protocol. A standard network protocol standard used to transfer files from one computer or host to another over a network that uses the TCP/IP communications protocol. FTP is therefore frequently used to transfer files over the Internet.
FSF Free Software Foundation. A non-profit foundation that supports free software. It wrote an operating system, GNU, that is similar to Unix but is free to all users. The General Public License (GPL) was written for distribution with the operating system but is frequently used for other free software packages.
FPGA Field programmable gate array. An integrated circuit that can be programmed by users after the circuit is manufactured.
Gateway Address A gateway address is the default address of your network or web site. This is usually the next address in line when connecting to the Internet from a local area network and is usually the address assigned to a router or a firewall. Communications traffic goes out and comes in through the gateway.
GPL GNU Public License. A license offered by the Free Software Foundation that covers licensing and distribution of free software.
GSM Global System for Mobile Communications. Standard developed in Europe to describe second-generation (2G) digital cellular networks. Digital cellular networks currently number up to 4G. The GSM standard is the most widely used digital cellular network standard.
HTTP/HTTPS Hypertext Transfer Protocol. Communication protocols that access the world-wide web. HTTP protocol is not secure. HTTPS is secure. The S designation means that the transfer protocol is combined with the Secure Socket Layer/Transport Security Layer (SSL/TLS) protocol to provide secure communication for transactions such as payments across the Internet.
Internet Protocol (IP) Address An IP address is a unique number that every device that connects to the Internet must have. Devices include personal computers, printers, removable hard drives, routers such as the WebPort, hardware firewalls, cell phones, and modems. The addresses are assigned by your system administrator or by the protocol that is running on your device. The connection method you choose defines how that address is assigned.
Local Area Network (LAN) A local area network (LAN) is a network that is normally made of devices such as personal computers that are located near to each other, such as in the same office building or plant.
LED Light-emitting diode. Photons emitted from a semi-conductor provide indicator signals for electronic devices and various forms of lighting. An LED can emit light photons in different colors, including red, green, and purple, and different frequencies (visible, infrared, and ultraviolet).
MAC Media Access Control address. A unique set of numbers assigned to a network interface card and stored in the read-only memory. A MAC address may also be called the Ethernet hardware address or the physical address of a device.
MII Media independent interface. Provided a standard interface used to connect a MAC fast Ethernet block to a PHY chip.
MODEM Modulator/demodulator. A device that encodes digital information in an analog carrier signal, transmits the signal, then decodes the information to reproduce the original data.
MUX Multiplexer. A device that selects among several different analog signals, and forwards the selected signal via a single output or line.
NAT Network Address Translation. Used for port forwarding and 'masquerading'.
PLC Programmable logic controller. A digital computer used to automate industrial processes such as controlling electrical turbine operation, assembly lines, and manufacturing machinery. The controllers are frequently ruggedized to withstand difficult operating environments.
PHY Physical layer that connects to a media access control address.
SCADA Supervisory control and data acquisition. Refers to data exchanged between computer systems that monitor industrial, facility, or infrastructure processes. Examples include oil refining and refineries, airports, railroad systems, and waste water treatment or power plants.
SMS Short message service. A text message that can be exchanged using cell phones, emails, or devices that have access to the Internet, such as routers, computers, or programmable logic controllers.
Static IP Address A permanent IP address assigned to a computer by the network administrator or a domain name server.
TFTP Trivial File Transfer Protocol.
Transmission Control Protocol, Internet Protocol (TCP/IP) Transmission Control Protocol, Internet Protocol. A group of communications protocols used to communicate between computers on the Internet or other networks. Also called The Internet protocol suite. The suite sends data across the Internet in packets.
Virtual Private Network (VPN) A virtual private network (VPN) is a secure communications network that uses external telecommunications methods to transfer data. You normally use a VPN to 'tunnel' through the Internet from an internal network (LAN) to a remote site, or to access your LAN from a remote site. The protocols used to communicate this way are normally encrypted using such methods as using passwords and encryption keys. It is very hard for external users to detect the network using packet sniffing or traffic intercepts. It is also very hard to mimic (spoof) the identity of a user on a VPN.
World Wide Web (WWW) The World Wide Web consists of a vast reservoir of documents on computers located around the world. These documents use hypertext and links to connect with each other via the Internet. Users with access to the Internet can access and view these documents on their own computers or other devices. The documents may include text, images, videos, files, and sound files, and are viewed using browser software packages that read the hypertext and display the resulting web pages on local computers or other devices.

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