Resources

Definition: A program written to take advantage of the ability of 386, 486 and Pentium processors to process 32 bits of data at one time. These programs will only run on Windows 95 or Windows NT, since these 2 operating systems are the only ones that also take advantage of the CPU's 32 bit capability. A 32 bit program should perform much better than it's 16 bit counterpart on the same hardware.

Definition: A new term for an OCX (see definition of an OCX) -- Microsoft coined this term in 1996 to 'repackage' and 'remarket' OCXs. When OLE first showed up 4 years ago, it was slow and buggy. Not the case now. But to get around any negative press, Microsoft gave them a new name. ActiveX controls, as they are commonly called, behave just like OCX objects. They have properties that can be set, and they can be accessed/manipulated by other objects. For example, a GE SNPx ActiveX control can be setup to read data from a specific PLC. Other objects, for example, a bar graph on the screen, can access data points from the ActiveX object by simply specifying the name of the object and the PLC register tagname to link to.

Definition: Application Programming Interface: Often also called "hooks and handles", an API is a documented set of function calls that a programmer can use when writing in C++ or Visual Basic, or other languages to connect or interface to an existing program and access data, add functionality, etc. If someone is talking about using an API, they are probably a bit more comfortable working with a group of function calls and the programming techniques required to use an API.

Definition: The standard for representing letters and other characters with numbers. Every letter and has a unique ASCII code. In the rawest form of some serial communications, data is sent as a stream of characters in a formatted way - i.e. -- data is always sent in the same order, the same # of characters ,etc. with each item being a number (the ASCII code). Because of the consistency, the receiving device can pick out what it needs and covert the codes back to characters/letters for use.

Definition: The speed at which devices communicate. Specified in "Bits per second". Kbaud refers to "1000 bits/second". So, when you hear a modem talks at 28.8 Kbaud, that means it can move 28,800 bits of data per second. In industrial communications, RS-232 or RS422/485 is limited to 19.2 Kbaud max. Some propriety networks, such as GE Genius, talk at 153.6K baud. Ethernet talks at 10 Megabaud, or 10 million bits per second.

Definition: A device level communication network based on a chip called the 'CAN' chip. This type of network has emerged in the last 3 years for use in connecting devices such as proximity sensors, photoelectric sensor, motor starters, and other traditionally low level devices to controllers such as PLC's or PCs. When you use a CAN network to connect these devices to a PLC, you no longer need to use I/O modules and hard wiring. There are 2 major variants of the CAN network that use different protocols -- DeviceNet and SDS. (see related definitions)

Definition: A process that involves providing a command to do something, obtaining feedback on the results, and acting again until a setpoint is achieved. For example, in driving a car, you are the controller. You control speed using the gas pedal and brakes and your feedback device is the speedometer. If your setpoint is 55 MPH, you adjust gas and brakes until you reach that speed. Your cruise control is an automated controller -- it does whatever it can to hold speed at the setpoint you give it, until you turn off the cruise control or hit the brakes.

Definition: Microsoft's specification that defines how program objects should be written, setup, and interact.  OPC Specifications before OPC UA were based on the COM specifications

Definition: A communications port -- a place on a computer or control used to connect to other computers or controls for communicating between the two devices. Comm Ports can be RS-232 or RS-422 or RS-485, which are standards for the electrical connection between the two devices. (see related definitions). The connectors used by comm ports come in a variety of sizes and shapes --- be sure to understand what you are connecting to.

Definition: The language used to allow two electronic devices to communicate with each other. Every device that communicates uses some protocol. Just because someone says a device is RS-232 compatible, doesn't mean your device can talk to it. Remember, the RS-232, RS422, RS485 standards only define electrical connections, not the language( protocol) spoken. Examples of protocols are: Modbus RTU/ASCII, GE SNP, GE SNPx, GE CCM, AB DF1, Siemens H1, Devicenet, SDS, and many many more.

Definition: Programs are written in some language, usually in a text form. In order for the PC to run the program, it must be converted into code that the PC CPU can understand and use efficiently. A compiler performs this function, along with providing testing and debugging tools. Common compilers for the 'C' language (most common language used for PC programs), are Microsoft 'C', 'C++', Visual Studio 'VB' and 'C#' , Borland 'C',

Definition: Allen Bradley's proprietary communications network. Almost all of AB's PLC's can talk on Data Highway (older) or Data Highway Plus (newer). When interfacing a PC to data highway, some form of interface card must be put into the PC. There are a variety of types of cards, including KT, KT-X, 5136-SD, and more. Also, AB sells boxes that convert from the Data Highway cable to standard RS-232 or RS-485, allowing you to connect a PC using a built in RS-232 port. The downfall of doing this is that it is slower -- much slower, with a max speed of 19.2 kbaud

Definition: Software Tools that can gather data from plant floor devices over a variety of network types and communications protocols and save the data in an organized fashion on a PC hard drive or in a open Data Base.

Definition: Dynamic Data Exchange - Microsoft's 1st attempt at sharing data between applications. It was very easy to use and setup to have a value in a word document to be affected by a value in a cell in excel. Anytime the data in Excel changed, the number in the word document would change. Setting up DDE links was easy - all you specified was the application name (the server), file name (the topic), and the item to be shared. (the item) DDE's downside was that it was slow.

Definition: Distributed Control System. The term came about because it referred to large process control systems that literally distributed the control of a plant out to controllers close to the processes, but provided centralized supervisory control from one place. DCS systems were traditionally found in process plants, such as chemicals, petroleum, paper mills, power plants, and pharmaceuticals. The traditionaly DCS cost in the several 100K to over $1 million. Names such as Fisher PROVOX, Bailey Net90, Westinghouse WDPF, Foxboro IA, Honeywell TDC3000 are common. Today, many DCS systems are coming down in price and trying to compete against PLCs. Likewise, PLCs are being combined w/software like Factorylink to provide the same functionality as DCS systems at a fraction of the price.

Definition: The program that wants the data from the DDE server. For example, if you have a value in Word that came from an Excel spreadsheet via a DDE link, MS Word is the DDE client. In the PLC world, if you're displaying a data point from your GE PLC in Wonderware InTouch - InTouch is the DDE client, and the GE PLC device driver is the DDE server. Clients get data from servers.

Definition: In the DDE data sharing model (see DDE definition), the DDE server is the application that has that data that you want -- it controls the data. For example, if you're displaying a value calculated in a Excel spreadsheet in Word, then Excel is the DDE server. In the PLC world, the program that talks to the PLC, such as a GE 90-30, is called the DDE server. Servers provide data to clients that request data.

Definition: The protocol for use on CAN bus networks that was developed by and promoted by Allen-Bradley. Now, the DeviceNet standard is administered by an independent consortium called the OpenDeviceNet group.

Definition: Software tools used to check on how well or not well another program or device is running. For example, IntraVue is used to determine how well and Ethernet Control Network is working

Definition: Dynamic Link Library. A software module that is only 'called' or used when needed. It is 'dynamically' loaded and removed from memory as needed. By using DLL's programs can function more efficiently and with less RAM memory. Most programs that use DLL's and want other programs to be able to interface with them will document their DLLs. That is, they will tell programmers how they too can "call" or use these program pieces when their programs need them. If a person is talking about using DLL's, they better know 'C' programming, as that is how almost all DLL's are used - they are called by 'C' programs.

Definition: The standard that defines the electrical connections between devices on a high speed network. Ethernet is the most commonly used network method for PC networks. The Ethernet standard defines the cable type, connection type, and the speed of the network. There are a variety of cable types, each with it's own advantages and distance limitations. For example, 10-Base-T is a twisted pair cable that uses phone-like connectors; 10-Base-2 uses coaxial cable with round BNC type connectors. There are other cable types also such as Thicknet, 10-Base-5, and more.

Definition: Proprietary extensions to DDE created by Wonderware to address speed issues. The best DDE servers for Wonderware InTouch are written using the FastDDE toolkit that Wonderware created.

Definition: In telecommunication, duplex communication means that both ends of the communication can send and receive signals at the same time. Full-duplex communication is the same thing. Half-duplex is also bidirectional communication but signals can only flow in one direction at a time. Simplex communication means that communication can only flow in one direction and never flow back the other way. An ordinary telephone conversation is a duplex communication. Most inexpensive speakerphones in conference rooms are half-duplex communication. (If you're speaking, you can't hear anyone else interrupt. You have to pause to let others speak.)

Definition: GE Fanuc's proprietary device communication network and their remote block I/O system. Genius blocks provide small amounts of I/O at remote locations. The Genius LAN provides high speed communications between the PLC CPU and the I/O blocks and between CPU's and PC's. To interface your PC to a Genius network, you'll need a special board, called a PCIM board, from GE.

Definition: In telecommunication, duplex communication means that both ends of the communication can send and receive signals at the same time. Full-duplex communication is the same thing. Half-duplex is also bidirectional communication but signals can only flow in one direction at a time. Simplex communication means that communication can only flow in one direction and never flow back the other way. An ordinary telephone conversation is a duplex communication. Most inexpensive speakerphones in conference rooms are half-duplex communication. (If you're speaking, you can't hear anyone else interrupt. You have to pause to let others speak.)

Definition: Human Machine Interface, once called MMI. Refers to the method used for operators to provide input to machines and receive feedback. In it's lowest form pushbuttons and indicator lights constitute an HMI. Today, HMI is used to refer to some type of electronic device that interfaces to the machine controls. You're most likely to hear about HMI software -- programs such as Wonderware InTouch, Siemens WinCC and US Data Factorylink that provide a graphical interface using a PC and a monitor & mouse or touchscreen with the machine controls.

Another HMI/SCADA package. Intellution is the name of the company that develops the product. You'll also hear the product referred to as "The FIX".

Definition: The most common and defacto standard for the expansion slots in your PC. The ISA bus standard defines the physical and electrical connection between your PC and expansion cards.

Definition: Local Area Network. The term can be used when refering to networked PCs (most common), but is also used on the plant floor to refer to plant floor networks such as GE Genius, AB Data Highway, Modicon Modbus Plus., etc. The LAN provides the method of physical connection between the computers, but it also defines the language of communications. For example, Novell Netware is a PC LAN. Windows NT with Ethernet and TCP/IP is another PC LAN.

Definition: The process of adjusting the parameters that are used in a process control loop (i.e. a PID loop - see definition) so that the controller adjusts the process to new setpoints smoothly and rapidly, and maintains the setpoint. In the car example, it would be like going under the hood and adjusting your cruise control device so that it handled changes in the road (i.e. hills) and kept you at constant speed, and moved up smoothly to new speeds when you pressed the accel button

Definition: In the master/slave communications method (see definition), the master initiates and controls all communictions with the slave.

Definition: Man-Machine Interface. Sometimes now called HMI, or Human Machine Interface, to be more politically correct. Refers to the method used for operators to provide input to machines and receive feedback. In it's lowest form pushbuttons and indicator lights constitute an MMI. Today, MMI is used to refer to some type of electronic device that interfaces to the machine controls. You're most likely to hear about MMI software -- programs such as Wonderware InTouch and US Data Factorylink that provide a graphical interface using a PC and a monitor & mouse or touchscreen with the machine controls.

Definition: The proprietary, high speed network used by Modicon brand PLC's. LIke AB Data Highway and GE Genius, Modbus Plus requires a special card in your PC if you want your PC to talk to the network. The most common one is called an SA-85 card.

Definition: A serial device communications protocol developed by Modicon for use with it's PLCs. Since then, it has been adopted by RTU (see definition) manufacturers as the "de facto" standard for communications with RTU's and many other serial devices. Modbus RTU uses RS-232 or RS-422/485 electrical connections.

Definition: A type of communications connection between devices that allows multiple devices (i.e. PLCs) to talk to a single device (i.e. - your PC) over a single cable. Each PLC is a "drop" and since there are many of them (up to 32 in the GE case), the cabling connection is a "multi-drop"

Definition: A term used in PC to PC networking. NetBIOS refers to the networking support that is built into every PC at a very low level -- in the BIOS (Basic Input Output System), the chip on every PC that defines how the pieces of the PC -- keyboard, mouse, hard drive, disk drives, comm ports, expansion slots, etc -- work together. Many software packages will say "works with any NetBIOS compatible network", which means it is leaving the networking tasks up to the BIOS and the network software and expects information to be presented to the program in a standard way.

Definition: A method of writing software that breaks down the program into individual pieces or modules that perform certain tasks. These pieces/modules are called objects. All of the objects can interact with one another to accomplish a certain task. Modules are re-useable from one program to another, saving greatly in program development costs. Each object has properties(see definition) that define how it works and how it interacts with other objects.

Definition: OLE Object -- An OCX is an software object that can be embedded into any Microsoft Windows product that supports Object Linking and Embedding (OLE). OCX's can be 16 or 32 bit, though most today are 32 bit.

Definition: Object Linking & Embedding: The term Microsoft coined for their technology that allows you to embed documents, parts of programs, etc. created with one Windows program in to another. For example, using OLE, you can embed an Excel spreadsheet into a Word document. If you want to edit the spreadsheet, you just double click on it, and your menus change over to the Excel menus, and you edit the document in place, without ever leaving word.

Definition: Using a standard PC, running a PC operating system, such as DOS, Windows, Windows95, WIndowsNT, or OS/2 to control a manufacturing process. Usually, some type of industrial I/O will be used to connect to field devices. For example, you can use a $99 card to connect 90-30 PLC I/O racks to your PC and use ASIC-100 for Windows NT software to control your process.

Definition: A method of communications between two devices where either device can initiate communications. The devices are "peers" because each has the same rights in the communications exchange.

Definition: A method of communications between two devices where either device can initiate communications. The devices are "peers" because each has the same rights in the communications exchange.

Definition: In the world of object oriented programming, every programming object has properties that define how it will function and respond to commands from other objects. For example, in a GE SNPx OCX object, the properties are set to define how the program will communicate to GE PLC's that are connected to the PC and how the program will share data with your other programs that display the data

Definition: A standard defining the electrical connection between devices. All PC's have RS-232 ports. Your mouse connects to an RS-232 port. Your external modem connects to an RS-232 port. RS-232 is used for single device to single device communications over short distances (< 50 ft) usually.

Definition: A standard defining the electrical connection between devices. RS-422/485 connections are used in cases where many devices of the same type (i.e. GE PLC's), need to talk back to a single computer over a single cable. RS-422/485 is often called a 'multidrop' connection (see related term). RS-422/485 connections can often be as long as 10,000 feet. RS-422/485 are also sometimes called differential because of the way the signals are sent on the line.

Definition: Remote Terminal Unit. A term that has been around a long time in applications such as waste water, where there are many remote stations that must be controlled and monitored. An RTU handles the control of a remote station, independent of the central control, but is able to respond to requests/commands from a central controller. RTU is also used to refer to the standard communications protocol that many RTU's use -- Modbus RTU (see related definition)

Definition: Supervisory Control And Data Acquisition. A term referring to a type of software that is used to gather data from plant floor devices and provide the ability for operators and supervisors to control large parts of a plant or process from a single computer screen. Examples include US Data Factorylink, Intellution's FIX, Citect, and Wonderware InTouch.

Definition: Honeywell/Microswitch's protocol for use with the CAN bus network (see related definition). SDS stands for Smart Distributed System.

Definition: In telecommunication, duplex communication means that both ends of the communication can send and receive signals at the same time. Full-duplex communication is the same thing. Half-duplex is also bidirectional communication but signals can only flow in one direction at a time. Simplex communication means that communication can only flow in one direction and never flow back the other way. An ordinary telephone conversation is a duplex communication. Most inexpensive speakerphones in conference rooms are half-duplex communication. (If you're speaking, you can't hear anyone else interrupt. You have to pause to let others speak.)

Definition: In device communications, a slave device can only respond to requests for communication from a master device (see definition).

Definition: Statistical Process Control. In product manufacturing, quality is of great interest. To quantify product quality, and then be able to use the results to alter the manufacturing process to improve the product, you need a defined method. SPC defines specific formulas for how to sample product and how to calculate statistics to provide meaningful results. In today's computerized world, there is little reason to have to do this manually (pen & paper & calculator) and little reason in some cases to have to manually capture the data needed for the calculations.

Definition: The protocol (language- see definition of protocol), used on the internet and many office networks that are using Windows NT to Windows 2014 servers and Windows 95,98 or Windows 3.11 (Windows for Workgroups) on user's desk.  This protocol requires a connection response to make a connection to a particular IP address or domain name which resolves to an IP address.

Definition: An Man Machine Interface or Supervisory Control and Data Acquisition package. US Data is the company. Factorylink is the product name. Factorylink has been around since the early 80's. Since 1992, most sales have been on OS/2 or Windows platforms. The latest version is called Factorylink ECS and runs on a variety of hardware/operating systems, including Windows 95/NT, OS/2, HP-UX, IBM AIX/6000, and more. Factorylink has a strong reputation for having many device drivers available from themselves or from third parties.

Definition: Visual Basic Extension --- a modular piece of software that works with Visual Basic and performs a specific function. VBX's are typically 16 bit tools, meaning they were developed originally to work with Windows 3.1 or Windows for Workgroups. Usually, VBX's will work with Visual Basic 3.0 or earlier, and any Windows 3.1 application that can call VBX's

Definition: A popular Human-Machine Interface package released in 1990