data communication- topic 2_2

8/3/2019 Data Communication- Topic 2_2

1/53

INTERFACE ELECTRICAL

TOPIC 2


2/53

Objective:

In the end of this course, students shouldbe able to explain the signal types andstandard interface communication.


3/53

Transmission media and physical layer


4/53


5/53

Guided Media

Guided media, which are those that provide a conduitfrom one device to another, include twisted-pair cable,coaxial cable, and fiber-optic cable.

Twisted Pair Coaxial Cable Fiber Optic


6/53

Twisted Pair


7/53

Two types of twisted pair cable


8/53

UTP connector
http://en.wikipedia.org/wiki/Image:UTP_ethernet_cable_8pin_modular_jack_endings.jpg


9/53

Categories of unshielded twisted paircable.

Category Bandwidth Data Rate Digital/Analog Use

1 very low < 100 kbps Analog Telephone

2 < 2 MHz 2 Mbps Analog/digital T-1 lines

3 16 MHz 10 Mbps Digital LANs






10/53

COAXIAL CABLE


11/53

BNC connector


12/53

Categories of coaxial cable


13/53

FIBER OPTIC


14/53

Optical Fiber


15/53

Fiber types


16/53

Fiber optic cable connector


17/53


Electrical interface is one of two related standardsthat can be used to physically interconnect computerdevices.

Interface includes not only connector and pinout, but

consists of three parts:

Connector Pin assignment Electrical characteristics


18/53


Interface description may include data format,data rate, cable length, mode of transmission,termination, bus common mode range, connector

type, and system configuration.


19/53

Why do we need the standard interface?

To enable devices from differentdistributors communicate each other.


20/53


The connector is defined by it shape, size, amount ofpins it holds and the place the pins are mounted inthe connector housing. Mostly it is built up of a shell(which contains the pins), the pins, the hood and

something to mount it with like screw-locks orlatches.

Thepin assignmentdescribes which pin isconnected to which circuit and thus describes theactual function of signal at the pin.

The electrical characteristics describe the voltages,currents and shapes of the signals.


21/53


There are some standardization organizationsresponsible for many common interfacesstandards:

TIA/EIA (Telecommunications Industry Association/Electronics Industry Association)

ITU (International Telecommunications Union)

CCITT (International Telegraph and TelephoneConsultative Committee) - now replaced by theITU

MIL-STD (United States Military Standards)

FED-STD (Federal Telecommunications Standard Committee)


22/53

ELECTRICAL SIGNAL

RS 232C/V.24

RS 422

RS 423

RS 449


23/53

RS 232C/V.24-serial interface

specification defines both the Mechanical,Electrical, and Functional characteristics.

RS-232 is the standard serial communicationsinterface found on all types of equipment such as

computers, modems, printers, Microcontrollers,eprom programmers, and a host of otherdevices.

Identical to the CCITT V.24/V.28, X.20bis/X.21bis

and ISO IS2110 standards.

RS232 defines the interface layer but not theapplication layer.


24/53

RS232 key features

Single-Ended

Point-to-Point Interface

Fully Defined Interface

20 kbps Maximum Data Rate (commonly usedvalues are 300, 1200, 2400, 9600, and 19200baud.)

Max distance- 15 m (50ft)


25/53

RS 232 details

RS-232 standard defines electrical signalcharacteristics (voltage levels, timing, signalingrate, short-circuit behavior, cable length),mechanical characteristics of RS-232 interface andRS-232 pinouts and connectors.

RS-232 data transmission consist of time-series ofbits. Both synchronous and asynchronoustransmissions are supported, but asynchronous linksending seven or eight bits packets is mostcommon configuration on PC.

RS-232 devices may be classified as DTE or DCE -this defines which wires will be sending andreceiving each signal.


26/53

EIA232 communication function and connector types for a personal

computer and modem.


27/53

RS-232 connector

DB 25


28/53

DB 9


29/53

Applications

Telecommunication application-cellular Network Performance Testing

Transportation application- VehicleDiagnostics

Telecommunication application-Bluetooth serial adapter
http://www.quatech.com/catalog/bluetooth_serial.php


30/53

Applications

Banking- Bank Teller Station

Socket serial USB to Serial Adapter


31/53

RS-232 signals

The RS232 pinout signals are represented byvoltage levels with respect to a systemcommon (power / logic ground).

The "idle" state (MARK) has the signal levelnegative with respect to common, and the"active" state (SPACE) has the signal levelpositive with respect to common.

RS232 has numerous handshaking lines(primarily used with modems), and alsospecifies a communications protocol.


32/53

Electrical specifications:

Voltage level :

a) Transmitter :logik HI 1 = 5 V to 25 Vlogik LOW 0 = + 5 V to + 25 V

b) Receiver :logik HI 1 = 3 V to 25 Vlogik LOW 0 = + 3 V to + 25 V

c) Noise margin: ( 5 3 ) V = 2V


33/53

RS-232 Voltage Levels


34/53

Signal State Voltage Assignment

Voltages of-3v to -25v with respect to signal ground (pin 7) areconsidered logic '1' (the marking condition), Voltages of+3v to +25v are considered logic '0' (the spacing condition). The range of voltages between -3v and +3v is considered a transition

region for which a signal state is not assigned.


35/53

example

One byte of asynchronous data


36/53

Signal Definitions

Signal functions in RS 232 can be divided intosix categories.

1. Signal ground and shield.

2. Primary communications channel.

3. Secondary communications channel.

4. Modem status and control signals.

5. Transmitter and receiver timing signals.

6. Channel test signals.


37/53

Signal Definitions

1. Signal ground and shield. Pin 1 , 7.

2. Primary communications channel. This is used for data interchange, and includes flow

control signals. Pin 2, 3, 4, 5.

3. Secondary communications channel. When implemented, this is used for control of the

remote modem, requests for retransmission whenerrors occur, and governance over the setup of theprimary channel.

Pin 13, 4, 16,19.


38/53

Signal Definitions

4. Modem status and control signals. These signals indicate modem status and provide

intermediate checkpoints as the telephone voicechannel is established.

Pin 6, 20, 8, 12, 22, 23.

5. Transmitter and receiver timing signals. If a synchronous protocol is used, these signals

provide timing information for the transmitter andreceiver, which may operate at different baud rates.

Pin 16, 17, 24.


39/53

Signal Definitions

6. Channel test signals. Before data is exchanged, the channel may be tested

for its integrity, and the baud rate automaticallyadjusted to the maximum rate that the channel cansupport.

Pin 18, 21, 25.


40/53


41/53

Pin Name Function Direction of transmission

DTE DCE

Data Signal 3 RD Received Data

2 TD Transmitted data

Ground Signal 7 SG Signal Ground

1 GND Protective Ground

Timing Signal 15 TC Transmit Clock

17 RC Received Clock

24 XTC External Transmit Clock

Control Signal 4 RTS Request to send

5 CTS Clear to send

6 DSR Data Set Ready

8 CD Carrier Detect

20 DTR Data Terminal Ready


42/53

DSR - Data Set Ready- pin 6- DCE to DTE- Used by the DCE to signal to the DTE that it is ready for

operation and ready to receive data.

DTR - Data Terminal Ready- pin 20- DTE to DCE- Used by the DTE to signal to the DCE that it is ready for

received data.

RTS - Request To Send- pin 4- DTE to DCE- Used by the DTE to signal the DCE that it may begin

sending data.

CTS - Clear To Send- pin 5- DCE to DTE- Used by the DCE to signal the DTE (after received RTS signal)

that DTE may begin sending data.


43/53

TXD: Transmit Data; The data sent from the DTE and received bythe DCE.

RXD: Receive Data; The data sent from the DCE and received by the

DTE.

CD: Carrier Detect; Used by the DCE to indicate to the DTE that theDCE has detected a carrier (of another device).

RI: Ring Indicator; Used by the Data Set to indicate to the Data

Terminal that a ringing condition has been detected.


44/53

RS 449/ V.35 / EIA/TIA-449

Purpose for cabling and pin-out to form a completeinterface

37-Position Interface for Data terminal Equipment and DataCircuit-Terminating Equipment Employing Serial binary DataInterchange

EIA-449 cabling uses EIA-422 differential pairs to send and receive data EIA-423 single-ended lines to send and receive control signals.

Data RateCable Length 2 Mb/sec 15.24 Meters

1 Mb/sec 30.48 Meters 512 Kb/sec 60.96 Meters 256 Kb/sec 121.92 Meters 128 Kb/sec 243.84 Meters 56 K 487.68 Meters 1.2 Kb/sec 914.40 Meters


45/53
http://rs449%20bus%20connector%20pin%20out.docx/


46/53

Pin Signal Name

Signal

Function Pin Signal Name

Signal

Function

1 Shield Ground - - -

2Sec Receive

ReadyControl from

DCE6

ReceiveCommon

Ground

3 Sec Send Data Data to DCE 7

Sec Request to

Send

Control from

DCE

4Sec Receive

DataData from DCE 8

Sec Clear toSend

Control fromDCE

5 Signal Ground Ground 9 Send Common Ground

EIA-449 9 Pin Connector Pin Out


47/53

RS 422

is a balanced serial interface for the digitaltransmission.

advantage- greater immunity to noise max. Distance @ Rate

-1200 meter/ 4000 feet @ max. 100 kbps

max. Rate @ Distance -10 Mbps @ 15 meter/ 50 ft driver Output Resistance

100 ohm

receiver Input Resistance

4 kohm min. max. Output Current

150 mA


48/53

4. Electrical specifications:

a) Transmitter:Logik 0 : + 2 V to + 6 V

Logik 1 : - 2 V to - 6 V

b) Receiver:

Logik 0 : +0.2 V to + 6 V

Logik 1 : - 0.2 V to - 6 V

c) Noise margin : ( 20.2 )V =1.8 V


49/53

RS422 Voltage Transition Levels


50/53

RS 423 / EIA/TIA-423

Specifies the electrical characteristics ofthe unbalanced (Single-Ended) interface

that may be employed when specified forthe interchange of serial binary signalsbetween DTE and DCE or in any point-to-point interconnection of serial binary

signals between digital equipment

EIA-423 is used in EIA-449 and EIA530.


51/53

EIA/TIA-423 Switching Levels


52/53

Exercises

1. State the meaning of electrical interface and its application indata communication.

2. Given :

Data: 11001100

Interface: RS 232C

Method of transmission: Serial Asynchronous

Parity: Even

Based on the information given above,

i. State the voltage level for bit 1 and 0.ii. State the start bit, parity bit and stop bit.

iii. Sketch the shape of the output waveform.


53/53

Exercises

3. List out two(2) organizations that are responsible to form thestandard of interface connection between DTE and DECE.

4. Explain two (2) characteristics of RS 232C/ V.24 on electricaland mechanical specifications.

data communication- topic 2_2

Documents