IBM Computer, Laptops and Servers

- A switch that normally selects a primary data path for serial connections, the selects a secondary data path if the primary data path is lost. The B B fallback switch supports this mode, or can select the primary data path until the alternate data path is activated, it then selects the alternate path until the alternate device is finished, then the primary data path is reselected. The B B fallback switch can also be used as a port combiner that selects the primary or alternate when data is ready for transfer, locks out the other path until transfer is completed. monitor

- A standard set of Facsimile (FAX) machine commands supported by some FAX/Modems. Fax Class 2 Commands - An extended set of Facsimile (FAX) machine commands supported by some FAX/Modems. Female (Connector) - Connector which has a receptacle socket (holes) for pins. When F follows the connector type, the connector is a female connector. desktop

- Light transmission through flexible transmissive fibers for communications, imaging, or lighting. Offers significant distance, bandwidth, isolation, and EMI/RFI immunity over traditional copper installations. Fiber Optic Converters - A signal converter with fiber optic transmitter and fiber optic receiver for the optical signals and electrical inputs outputs for another signal format such as RS-232, RS-422 or 2-wire or 4-wire RS-485. infosys

- First In, First Out - FIFO implies a queue and buffer to hold it. The oldest data item in the buffer is the first item retrieved. Contrast with LIFO (Last In, First Out) which operates like a data stack, items placed on the stack are retrieved first in the order of last first. Full Duplex - A full duplex communications system is able to transmit and receive at the same time. Two communications paths are provided, one for each direction. Examples are RS-232, RS-422 and 4-wire RS-485. (2-wire RS-485 is half duplex) refurbished laptops

- A connector with dual male or dual female connectors wired pin for pin. Used to change or connect two female devices together (using dual male) or two male devices together (using dual female). GHz - Giga Hertz (Hz x 10 to the 9th power) - 1 GHz=1000 MHz GPS - Global Positioning System - A device which uses 3 or more of at least 24 satellites in orbit to determine the local position on earth of the receiver. 3 satellites are needed for a 2D fix, 4 for a 3D fix which includes altitude. Accuracy of position can vary depending on the location of the satellites used, altitude accuracy for civilian uses can vary by +/- 500 ft. Two frequencies are used, L1 (1575.42MHz) for civilian, L2 for military. The date and time are broadcast for positioning references to downloaded tables used to calculate the position. GPS receiver outputs are used in marine and land based navigation systems which interface to a computer through RS-232 or RS-422/485 serial connections. wipro

- When two or more devices are connected to a common ground through different paths, a ground loop occurs. Currents flow through these multiple paths and develop voltages which can cause damage, noise or 50Hz/60Hz hum in audio or video equipment. To prevent ground loops, all signal grounds need to go to one common point and when two grounding points cannot be avoided, one side must isolate the signal and grounds from the other. lap top

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1. A heavy solid or braided wire cable used to provide a low resistance path from a device to a earth ground. Used with surge suppressors. memory

2. A conductive wrist strap and grounding cord used to discharge static voltages to ground when handling ESD (Electro Static Discharge) sensitive devices such as interface cards. intel

- In a half duplex communications system a device can either receive or transmit, but not both at the same time. Many radio transmission systems are half duplex because the transmitter and receiver use the same frequency, and while transmitting mute the receiver. A RS-485 2-wire system is also Half Duplex because it uses the same pair of wires to transmit and receive. Handshake Lines - as400

1. In a RS-232 serial system, data flow control is performed using the CTS (Clear To Send) and RTS (Request To Send) control lines. The DSR (Data Set Ready) and DTR (Data Terminal) control lines are used to determine if a device is connected and active. Additional lines for DCD/CD (Carrier Detector) and RI (Ring Indicator) are used with modems. averatec

2. In a parallel printer interface, the primary printer handshake lines are Strobe (to printer) and Busy (from printer) and Acknowledge (from Printer). Additional lines are used to indicate Printer Select (printer ready), Printer Error, Paper Error, Reset. hardware

3. Other types of devices may have other handshaking signals, at least one signal is needed to indicate that data is ready to be read, and one signal returned to indicate that data can be received or not received. Some devices have a handshaking mode and a burst mode, data transfer is setup with handshaking, then transferred with a Acknowledge for each byte, which tells the sender to change the data byte. If Acknowledge is not received soon enough, burst mode times out. dual xeon

- The process of using handshaking lines or software data flow control such as X-On/X-Off to transfer each byte of data. Hardware Flow Control - storage

1. Serial Port transfer using the RTS and CTS control lines to control data flow instead of using software flow control using X-On/X-Off control with a full duplex serial link. seagate

2. Parallel data transfer in which handshaking for each data byte is handled automatically by the hardware rather than by computer instructions that alter each of the 4 hardware states computer sales

- Serial Port transfer using the RTS and CTS control lines to control data flow instead of using software flow control using X-On/X-Off control with a full duplex serial link. Hayes AT Commands - Modem commands that were popularized by Hayes in their telephone modems, the modem command started with AT for Attention modem. For compatibility with existing software applications, many other modem manufacturers copied all or part of the command set. computer hardware

- (VGA type) - computer video High Density 15 pin D type connector sized the same as DB9 except more pins Hub - A central connection point for multiple LAN devices in a Local Area Network, a central connection point for multiple USB devices in a USB network. For a USB network, expands the number of USB connections that can be made to one of the host USB ports. Provides one connection upstream, and usually 4 or more downstream connections. Upstream connections go to the host, downstream to additional devices. For a Ethernet Serial hub, provides network connection for multiple serial devices using RS-232, RS-422 or RS-485 signal formats. printers

- Hertz - the term adopted to indicate a rate of cyclic voltage alternations per second in AC (alternating current) signals. The term was formerly known as cycles per second which was abbreviated cps and could be confused with another scientific term with a different meaning. Used to indicate the frequency of AC power 50Hz, 60Hz or 400Hz, audio (16Hz to 20KHz) or radio waves such as 520KHz, 108MHz, 900MHz or 1.2GHz. technology

- Input/Output circuit boards or modules used for computer data acquisition or control, typically for digital I/O to read switch closures or control relays. IEEE 1284 - A set of standards for parallel printer port interfacing and cabling. A IEEE1284 printer cable meets the low capacitance requirements and can permit parallel devices which meet the standard to be separated by as much as 30 feet. mainframe

- A package which is based on the size of the DB25 or DB9 type connector. The package is about 0.9 inch thick by slightly more than the connector width/height, and is the length of a single or double length connector shell. DB9 Connector Shell DB25 Connector Shell Double DB25 Shell Infrared - Light energy which is just below the spectrum of red visible light. Infrared light is given off by heat sources and IR LED s or lights. The other end if the spectrum of visible light is violet, then Ultraviolet. samsung

- computer repair

1. The connection between computer and the outside world. Electrical interfaces can be serial, RS-232, RS-422, RS-485, USB-A Female, Parallel, or similar. used computers

2. A user interface provides a connection between the user and program. It includes the appearance of the screens, menus, mouse/keyboard keys for input/output. Windows provides standard methods for a program to use to build a user interface. network

- A converter from one type of interface to another. A converter performs conversion from one electrical format to another. RS-232 to RS-422 or RS-485 or back, RS-232 to fiber optic or back. Some converters handle hardware conversion between formats. Some require hardware and software to perform conversion. For example, Host USB to RS-232/422/485 or Ethernet to Serial. digital cameras

Compare a converter to an adapter. An adapter simply converts hardware connections, whereas a converter may also provide an electrical signaling change. A RS-232 signal may use DB25, DB9 or RJ-11 or phone plug or jack. The signal connector is adapted, not converted. desktops

Category 5 cable is available as shielded twisted pair (STP) as well as unshielded twisted pair (UTP) and generally exceeds the recommendations for RS-422 making it an excellent choice for RS-422 and RS-485 systems. cognos

Owners of newer laptops have already discovered that many of the computers are being shipped without standard 9 pin RS-232 Serial Ports. This was not an oversight, but part of an overall strategy to simplify the operation and improve information throughput in and out of a PC. hosting

The absence of the standard serial port on laptops will soon be evident on new desktop PCs. This will be gradually phased as part of a program called Legacy Removal . Legacy Technology is a term that was given to long used technologies that are being used for the most part because that is the way it has always been, but newer platform technology exists that outperforms the older equipment. A Legacy feature is defined by the industry, as one for which there is a faster, superior, easier and/or less expensive alternative available. netfinity

Major PC manufacturers and industry heavy weights like Intel and Microsoft have gotten together since 1999 to create what they term the Ease of Use Initiative , or the Easy PC Initiative . It is an industry initiative to make PCs more Consumer friendly and remove what they see is stumbling blocks to an even more widespread use of Personal Computers. internet

The Initiative sets out to identify these stumbling blocks and what it is about PCs that create frustration for first time users in particular as well as long time users of PCs. The effort is geared around changing these stumbling blocks into building blocks for a new generation of PCs. Some of these building blocks have been identified as, Instantly Available/ON NOW PC Technology , Small Form Factor , Universal Serial Bus (USB) , Legacy Removal , and Slotless Design Technologies . The coming generations of PC technology will be developed around the Four S s of Design: Speed, Security, Simplicity and Style. cheap computer

The elements of Speed and Simplicity are what bump the new design philosophy up against the Legacy Technology of the Standard RS-232 Serial Port. The effort of Legacy Removal has placed the Serial Port on a dead end track with standard PC development. The ease of external Plug-and-Play, as well as the data speeds needed for digital imaging, video conferencing, and other digital audio and video interfacing, has pushed the use of USB as the standard interconnect technology. digital camera

The existing PCs have separate external ports for the connection of a mouse, keyboard, and monitor, as well as ports for other peripheral devices. To connect each device, you must first locate the appropriate port for that particular device. With the implementation of an array of USB ports that automatically recognize the device that is connected, any port can be used for any device. The goal is to simplify connectivity and reduce the Out of Box time. This is to eliminate the intimidating idea of having to decipher a spaghetti full of wires before a PC can be unpacked and up and running. printer

A Legacy Removal Roadmap has been established at the Intel Developers Forum in 1999 for the phasing out of Legacy Technologies in PCs. The first to go in this timeline was the ISA slot, used for adding special function cards to the available PC slots. Intel s Legacy Removal Roadmap calls for the gradual phase out of other technologies. On the list for removal are the following: Gameport/MIDI, PS2, Serial, Parallel, IDE, Floppy, VGA, and eventually all user-accessible slots. xseries

The concept among developers is that there are a sufficient number of manufacturers making cross over technologies such as USB and PCMCIA to serial devices to provide for the continued use of existing serial technology devices. Like USB, Firewire or 1394 is a high-speed serial bus connection designed to interconnect PCs with Consumer Electronics. The targets are the high-bandwidth devices such as camcorders, digital videodisk players, and other high-speed peer-to-peer applications. Newer technologies that provide more reliable and less expensive alternatives will gradually lead to the elimination of the older technologies. As the communication speeds of peripheral devices increase, the use of USB or Firewire as the preferred interface will increase. maxtor

Devices with standard DB9 RS-232 connections will gradually diminish, to be replaced with higher speed connections. This will reduce the need to include them on standard PC designs. Referenced from Intel s Easy PC Initiative Home Products Partners Support Tech Notes News About Contact Site Map Privacy Policy Questions or Comments Copyright 2007 B B Electronics Mfg data storage

It depends on the two devices being connected, whether they are DTE or DCE devices, how they are connected together before adding a RS-232/RS-422 Converter, how many signal lines are required. This information is for devices requiring only Receive (Rx) and Transmit (Tx) signal only, other devices require more connection pairs. hitachi

CASE #1: The Device connects directly to the serial port on the Computer. The computer serial port is configured as a DTE port, the device cabling is configured as DCE to connect directly. With this connection, the first RS-422 converter connects with a Standard serial cable wired pin #1 to #1, #2 to #2, etc. The second converter requires a null modem connection between it and the device, since our converter is configured as DCE on the RS-232 side, and the device cabling is also DCE. See the connection diagram for CASE #1. rational

CASE #2: The Device connects through a Null Modem (Crossover) Cable to the serial port on the Computer. This original connection requires a Null Modem cable because both Computer and Device are configured as DTE. In this case, the first RS-422 Converter connects to the Computer with a Standard serial cable wired pin #1 to #1, #2 to #2, etc. The original Null Modem Cable is set aside, not used. A new Standard serial Cable is connected to the device and the second converter. See the connection diagram for CASE #2. websphere

CASE #3: In the third case, we want to extend a set of RS-232 connections between two devices, but we don t know how either port is configured. Both devices use DB9F (female) connectors. We have a voltmeter. We know the converters are DCE devices. When powered, the RS-232 output will have a negative DC voltage compared to GND. So, we connect a Standard cable to the device, power it up, measure between Pin #5 of the cable to Pin #3. If it has a minus voltage (usually between -3VDC to -11VDC), connect it to the DB9 connector of the converter. This connection should be okay. If almost no voltage on Pin #3, check Pin #2. If it has the minus voltage, use a Null Modem Connection between the device and converter to swap the pin connections. If neither has a voltage, you need pinouts for the connector/cable. Make a similar test for the RS-232 connections at the other end. The voltage should be on the cable pin connecting to Pin #3. No Connection diagram for CASE #3, it will either match CASE #1 or CASE #2, but could instead require connections with Null Modem Connections on both converters if the original cable is not used. battery

The pin numbers for the RS-422 connections are not shown, they may vary according to the model, but the signal name will be shown on the data sheet. In the case of DB25 RS-232 connections, Pin #2 is TD, Pin #3 is RD, and Pin #7 is GND. Note: These connection figures do not show power supplies or handshaking lines needed to power port powered converters. The port powered devices usually need the RTS line and DTR line high (signal level +11 VDC), a power supply may be required for both ends if the RS-422 transmitter voltage is less than 4.4 volts TD(B) to TD(A). For pinouts of RS-232, refer to the FAQ on RS-232 Connections that WORK!. it support

Tech Notes FAQ: Check RS-422 Port or Converter western digital

Perform a Loopback test using a Terminal program that lets you Open a serial port to send and receive characters. To check both inputs and outputs, the outputs are connected to the port inputs as shown in the table below. Loopback wiring is shown in Figures 1 to 8. RS-422 ports and converters that support 2 channels will have connections for only Receive and Transmit. A 4 channel device will add connections for the RTS and CTS handshaking channels. A 8 channel device adds DTR and DSR and CD or RI. CD and RI are typically supplied only by modems, outputs on the DCE device, inputs on the DTE device. music

Use ComTest from our Website to check serial ports assigned Com1 or higher under Windows. It can access Com ports 1-8, including USB serial devices. ComTest has simulated indicator lights for line status for RTS, DTR, CTS, DSR, and CD. It will let you set the DTR and RTS line high or low to check the inputs, or set DTR RTS high to power a port powered device or check loopback connections on devices which don t use handshaking. ComTest Features. networks

Use Simpterm from our Website to check motherboard or ISA based serial ports under DOS. Do not use SimpTerm with Windows. toner

1. Before starting, make a Directory Folder (such as Test) on your hard drive to use when downloading the program. cheap laptops

2. Go to the B B Electronics Mfg. Co. Website. http://www.bb-elec.com wholesale

3. From the software section of our technical library page, select ComTest brother