DeVRY INSTITUTE OF TECHNOLOGY

DIGITAL AND DATA COMMUNICATIONS ET270

Instructor: Tom Wheeler. Office - Room 208
E-Mail: twheeler@kc.devry.edu

Web Site: http://www.kc.devry.edu/homepages/twheeler

TEXT: Hioki - "Telecommunications" - 3rd. Ed.

CREDIT HOURS: 4.0

Major topics covered:

I. Networks - Fiber Optics - Digital Modulation - Serial Data

II. Asynchronous/Synchronous Communication - UARTs - RS232D Standard

III. Error Checking and Correction - Protocol - Networking Fundamentals

Industry, and the rest of the business world, depends heavily on the ability to communicate effectively. Industrial control systems are usually designed around computers, and these computers require effective communications links for safe and efficient operation. Banks and other corporations use computers to handle funds, and again, effective communications is a must. The Internet, once an exclusive tool of the scientific community, is now being used

for an incredible number of applications by all kinds of people. In this course we will examine the elements of these communications systems to see what makes them function (and sometimes, malfunction!)

Daily class attendance is required. You are responsible for the material presented in all class sessions, regardless of your presence or absence. Absence of more than 8 class sessions is cause for dismissal from the course, with a grade of F. You are expected to be on time for every class meeting. If you will not be able to make it to class on time, please call the instructor in advance to make arrangements.

Homework is due at the beginning of class (xx00 UTC). Late homework is not accepted unless mitigating circumstances are present. If this is the case, bring documentation (court papers, note on doctor's letterhead, etc.) Homework carries the weight of one major exam (100 points) in the course. Failure to do homework will do severe damage to your grade. (UTC=Universal Coordinated Time, or Standard World Time.)

There are 3 major exams, an unspecified number of quizzes given at random intervals, various homework assignments, and a final examination given in the 15th week of the course.Your grade will be determined as follows:

2 Best Major Exams @ 100 points each: 200 points (Sum of two best test scores)

Quizzes/Homework : 100 points (A percentage)

Final Exam (Comprehensive): 150 points

450 points total for course

90 - 100 % = A 80 - 89 % = B 70 - 79 % = C 60 - 69 % = D

<60 % = F

Copying the work of another, and claiming it to be your own is plagiarism. This includes (but is not limited to) copying others homework, copying from a lab manual or textbook, or collusion. The minimum penalty for cheating in any form is a grade of zero for the element involved; in some cases, failure of the course and/or expulsion from the Institute will also result. All cases of misconduct will be documented and forwarded to Student Services for disciplinary consideration. The DeVry Student Handbook contains complete information on this topic.

EMERGENCY PROCEDURES - Each classroom has a plaque (located near the door) with instructions for evacuation in the event of an emergency. The instructor will remain in charge of your class group should the situation arise.

FOOD or DRINK are not allowed in the classrooms and labs at DeVry.

Networks Chapter 1 (all)

Fiber Optics Chapter 18 pp. 519-523,

535-540,

548-563

Modems/Digital Modulation Chapter 13 pp. 319-346

Serial Data Formatting Chapter 8 pp. 155-160

(Exam #1)

UART Operation (TR1602) Chapter 5 pp. 104-123

RS232D Standard Chapter 8 pp. 160-195

(Exam #2)

Error Checking & Correction Chapter 17 pp. 497-516

Handout "Error Detection"

ISO/OSI Model Chapter 14 pp. 359-360

Synchronous Protocol:

BISYNC,HDLC/SDLC Chapter 14 pp. 360-387

(Exam #3)

LAN Introductory Topics Chapter 11 pp. 330-374

Internet Basics Chapter 16 pp. 455-494

Handout "TCP &IP Protocols"

Handout "The Web"

Handout "HTML 105"

The homework assignments for this course are given as part of this syllabus. Due dates will be determined in class.

OBJECTIVES FOR ET270 DIGITAL/DATA COMMUNICATIONS

This is a detailed listing of objectives for both the course and lesson level.

I. NETWORKS, DIGITAL MODULATION TECHNIQUES, FIBER OPTICS

1. Explain at least one purpose of Data Communications technology:

a) Digital communications over a distance

b) Digital communications through Analog medium

c) Analog communications through Digital medium

2. Identify the following types of networks, and name at least one important

characteristic of each one:

a) Point-to-point

b) Multi-point (Multi-drop)

c) Ring

d) Star

3. Define the following terms:

a) Protocol

b) Poll

c) Select

d) Simplex

e) Half-Duplex

f) Full-Duplex

g) Serial Data

h) Parallel Data

4. Explain how an amplitude-modulated fiber optic data link operates.

5. Define and explain the following fiber optic terms:

a) Acceptance cone angle

b) Numerical aperture

c) Dispersion

d) Specific Loss

6. Explain the relative advantages and disadvantages of LEDs and LASERs as

fiber-optic carrier signal sources.

7. Explain typical techniques for the following fiber optic procedures:

a) Splicing

b) Termination

c) Troubleshooting

8. Describe how data is transmitted using:

a) Frequency-Shift Keying

b) Phase-Shift Keying

c) Amplitude-Modulation Keying

d) Quadrature-Amplitude-Modulation (QAM)

e) Fiber Optic Techniques

9. Define, and give an example of, each of the following terms:

a) Transition (of a modulated waveform)

b) Data Rate

c) Signalling Rate

d) BAUD

e) Single-Level modulation

f) Modulation States

g) Multi-Level modulation

10. Given a modem with a stated number of bits per signal, and the

input data rate, calculate:

a) Output BAUD rate

b) Number of required modulation states (conditions)

11. Explain at least one factor that limits the rate of signalling in

a data communications system:

a) Available bandwidth of medium (usually phone line)

b) Frequency of carrier (Nyquist criterion)

12. Explain the relationship between noise immunity and number of

modulation states in a practical data communications system.

13. Define:

a) Pulse Code Modulation (PCM)

b) Sampling Period

c) Sampling Rate

d) Quantization

e) Resolution

f) Aliasing distortion

14. Draw a block diagram of a complete PCM analog signal link, showing:

a) Analog signal source and optional anti-aliasing filter

b) Analog-to-digital converter

c) Sampling clock

d) Storage and/or transmission media

e) Digital-to-Analog converter

f) Output smoothing filter

15. Explain the purpose of the RS232D standard.

16. For an RS232D signal line, give:

a) The allowable Voltage range for a logic "1" (OFF or MARK condition)

b) The allowable Voltage range for a logic "0" (ON or SPACE condition)

c) The absolute maximum voltages expected in normal operaton

17. Define the following RS232 signal-line abbreviations. State the

purpose of each line:

a) TD

b) RD

c) PROTECTIVE GROUND

d) SIGNAL GROUND

e) RTS

f) CTS

g) DSR (DCE READY)

h) DTR (DTE READY)

i) DCD or RLSD

18. For each signal line listed in objective #17, give:

a) Direction of signal flow, where applicable

b) The RS232 pin number

19. Given an RS232 pin number that corresponds to one of the signal lines

listed in objective #13, give the RS232 signal-name.

20. List and explain the sequence of events in the SEND SEQUENCE for half-

duplex devices on the RS232.

II. SERIAL DATA FORMATTING, UARTs, ERROR CHECKING AND RECOVERY METHODS

1. List the two main types of serial data, giving the defining characteristics

of each one.

2. Explain how asynchronous characters are transmitted and recieved.

3. Given the time for each bit-cell in an asynchronous character, calculate:

a) The data rate, in BPS

b) The character rate, in CPS, if given appropriate information.

4. Give the PURPOSE of each of the following structures:

a) Start bit

b) Parity bit

c) Stop bit

5. Demonstrate how the Parity bit is calculated, given a specific parity

setting (even or odd), and a number of selected data bits.

6. Given the appropriate parameter settings (BPS rate, number of data bits,

parity mode, number of stop bits), and a datum byte, draw a complete

asynchronous waveform, labelling all parts, as well as showing the

time dimension for each cell.

7. Given an asynchronous waveform, and the appropriate parameter settings

(BPS rate, number of data bits, parity mode, number of stop bits),

find the value of the data byte being transmitted.

8. Given an asynchronous waveform and a missing quantity (parity mode,

number of stop bits, number of data bits), examine the waveform and

determine the missing information.

a) This objective can only be completed when given the proper information

about the missing portions.

9. Given a symbolic signal name on the General Instrument AY3-1015 (equivalent

to TRW 1602) UART, describe the function of the signal. The following are

required:

NOTE: A "-" indicates ACTIVE LOW or NEGATIVE TRUE signal.

a) -RDE

b) RD1 to RD8

c) PE or RPE

d) FE or RFE

e) OR or ROR

f) DAV

g) -RDAV

h) RCP

i) TCP

j) SI

k) SO

l) EPS

m) NP

n) TSB

o) NB1, NB2

p) CS

q) DB1 to DB8

r) EOC

s) TBMT

t) -DS

u) XR

10. Given a set of requested parameter settings, show how the AY3-1015 UART

control pins should be connected to obtain the settings. This should

include:

a) TCP and RCP signal rates

b) NP, EPS, TSB, CS signal states

c) NB1 and NB2 signal states (if provided with lookup table for NB1, NB2).

11. Given a UART connected as in objective #10, determine the parameter

settings from the states of the control pins.

12. Draw a TRANSMIT timing diagram for the AY3-1015 UART. The following

signals should be on the diagram:

a) -DS

b) TBMT

c) SO

d) EOC

13. Draw a RECEIVE timing diagram for the AY3-1015 UART. The following

signals should be on the diagram:

a) SI

b) DAV

C) -RDAV

14. Describe how the AY3-1015 UART can be interfaced with a microcomputer

system as an I/O port (mapped in the I/O plane.) Description

will include:

a) Data bus connections

b) Address decoder and control bus connections

c) Software methods to access the UART

15. Explain why error checking and recovery methods are necessary for

digital communications systems.

16. Explain the difference between ERROR CHECKING systems and ERROR CHECKING

AND RECOVERY (ECC) systems.

17. Define:

a) Lateral Parity Check

b) Longitudinal Parity Check

c) Checksum

d) Block Check Character

e) Distance Code

f) Cyclic Redundancy Check (CRC)

g) Hamming Code

h) Frame Check Sequence

18. Given appropriate data, calculate:

a) Lateral parity

b) Longitudinal parity

c) Checksum

d) CRC

III. BISYNCHRONOUS PROTOCOL (IBM 3270)

1. List the types of networks 3270 protocol is used on.

2. Give the most common application for 3270 protocol.

3. Define the following terms as they apply to 3270 protocol:

a) POLL - Invitation to send

b) HOST - Mainframe Computer

c) TERMINAL - Input/Output device with limited computing potential

d) FEP - Front End Processor

e) SELECT - Notification of message waiting

f) EOT - End Of Transmission

g) ACK - Positive Acknowledge

h) NAK - Negative Acknowledge

i) WACK - Wait Acknowledge

j) RVI - Reverse Interrupt

k) SOH - Start Of Header

l) STX - Start Of Text

m) ETB - End This Block

n) ETX - End Of Text

4. Give the purpose of the signals in 3(f) through 3(n).

5. List the fundamental rules designed into the 3270 protocol. This list

should include:

a) The HOST system (or HOST FEP) controls all communications.

b) A terminal NEVER originates communications.

c) A terminal, if able, MUST answer.

d) Host may re-try failed communications with a terminal up to 2 times.

After that, the terminal is locked off the network.

6. List the physical features of a multi-drop network that a technician

takes advantage of when troubleshooting. This list should include:

a) All units "hear" when any single unit transmits. Much like a party line.

b) If any single unit locks its carrier on, the network fails.

c) Even if a unit is not actively passing data, the DCD light on the attached

modem should flicker several times a second, as it is "hearing" other

data transfers, as well as network supervisory signals.

d) If a unit is "alive" the RTS, TD lights on the modem should periodically

flicker, even if no data is being transferred. This is because the unit

is responding periodically to net supervisory signals.

7. Describe the operation of the POLL LIST.

8. Describe how character synchronization is acheived.

9. Describe the difference between the hardware function SYN and the

software functions of a protocol.

10. Given values for Poll and Select characters, as well as a desired unit

address, give a complete example of:

a) POLL sequence - Standard Select

b) SELECT sequence - Standard Select

11. List the complete message block structure for 3270 protocol (text mode).

12. List the message block structure for 3270 transparent mode.

13. Given a sample poll list, and queue of information to be dispatched, as

well as unit addresses, predict the complete action of a 3270 network

in STANDARD SELECT. The poll list must have at least 3 addresses.

IV. BIT-ORIENTED PROTOCOL

1. Given the structure of a bit-oriented protocol (such as X25, HDLC, etc), explain its operation.

V. LAN INTRODUCTION

1. List the basic physical components of a local area network.

2. Explain how LAN protocol operates in the following topologies:

a. Ring

b. Bus

3. List the software components necessary for operation of a LAN.

4. Explain how a LAN system is built, giving both hardware and software

details.

ET270 Digital/Data Communications

Homework Problems #1

INSTRUCTIONS: Use separate paper to return your answers. Box all

numerical answers. Use complete sentences for

written answers; write neatly (or type.)

1. Draw a block diagram of a general data communications system.

Label each part, and using outline form, describe the function

of each part. Use a template or straightedge for the block diagram.

2. Define the following terms:

(a) Network (b) Point-to-Point

(c) Multi-drop (d) Star

(e) Ring (f) Protocol

(g) Poll (h) Select

3. What is the difference between serial and parallel data? Use an

example (non-electronics) to explain your point.

4. What are the units of digital information flow? How is it

calculated?

5. What is the meaning of the term "BAUD?"

6. What are at least two advantages of fiber optics?

7. What is a disadvantage of fiber optics?

8. Explain how a light wave propagates or moves through a fiber. Does

it involve reflection or refraction?

9. Compare laser and LED light sources, giving at least two advantages

and two disadvantages for each one.

10. What device would be used as a very high speed photodetector in a

fiber-optic system?

11. Explain, drawing a simple diagram, at least two different methods

for splicing fiber optic cables.

12. What is meant by "single-level" modulation? What is the main

limitation of all single-level modulation systems?

ET270 Digital/Data Communications

Homework Problems #2

INSTRUCTIONS: Use separate paper to return your answers. Box all

numerical answers. Use complete sentences for

written answers; write neatly (or type.)

1. USING GRAPH PAPER, draw the following asynchronous waveforms:

(a) A5H sent 8,N,1

(b) 76H sent 7,E,2

(c) 06H sent 5,O,1

USE A STRAIGHTEDGE AND LABEL ALL PARTS OF THE WAVEFORMS.

2. Define the following terms:

(a) Asynchronous data

(b) Synchronous data

(c) Start bit

(d) Stop bit

(e) Parity

(f) Bit cell

(g) Idling

3. Explain the differences and similarities between synchronous and

asynchronous data.

ET270 Digital/Data Communications

Homework Problems #3

INSTRUCTIONS: Use separate paper to return your answers. Box all

numerical answers. Use complete sentences for

written answers; write neatly (or type.)

1. USING GRAPH PAPER, draw the serial output (SO) of the UART with respect to the EOC signal, for ONE character. Assume parameters are 8,N,1 and the data is E5H.

2. Explain the function of each UART signal named below, in your own words:

(a) DS

(b) EOC

(c) TBMT

(d) SO

(e) SI

(f) DAV

(g) RDAV

(h) RDE

(i) XR

3. Explain how double-buffering works in the UART TRANSMITTER, and draw

a simple block diagram to explain. (Be sure to explain how TBMT and

EOC are related.)

4. Copy the following table onto your own paper, and complete it. BOX your answers.

NB2 NB1 TSB NP EPS F(TCP) BPS CPS PARMS

-------------------------------------------------------------

| 1 | 1 | 0 | 1 | 1 | 9600 | | | |

-------------------------------------------------------------

| | | | | | | 1200 | | 7,E,2 |

-------------------------------------------------------------

| | | | | | | | 100 | 5,N,1 |

-------------------------------------------------------------

| 0 | 1 | | | | 1600 | | 10 | ?,O,? |

-------------------------------------------------------------

| | | | | | | 9600 | | 8,N,1 |

-------------------------------------------------------------

ET270 Digital/Data Communications

Homework Problems #4

INSTRUCTIONS: Use separate paper to return your answers. Box all

numerical answers. Use complete sentences for

written answers; write neatly (or type.)

1. Explain the primary purpose of the RS-232 standard. What situation
does it prevent?

2. The Kenwood TS-940 HF transceiver can be controlled with an add-on

RS-232 interface. Since the IBM-PCs in lab have built-in RS-232

ports, would communications be guaranteed between the two units?

Explain why or why not.

3. Draw a diagram that illustrates how RS-232 voltage levels are

interpreted. On your diagram, be sure to display the maximum

and nominal voltage levels, as well as their equivalent TTL

logic level. Also clearly mark the transition region.

4. (a) What does DTE stand for?

(b) Practically, name one device that can be a DTE.

(c) What type of connector is specified for use on a DTE?

5. (a) What does DCE stand for?

(b) Practically, name one device that can be a DCE.

(c) What type of connector is specified for use on a DCE?

6. For each of the following signals, give the following information:

* Signal Name ("unabbreviated")

* Pin Number on RS-232 Interface

* Functional description (including DIRECTION of signal flow)

a) GND

b) TD

c) RD

d) DCE RDY

e) DTE RDY

f) RTS

g) CTS

h) RLSD

i) PGND

7. Explain what is meant by a "crossover connection." Give an example

of a situation where one might be required.

ET270 Digital/Data Communications

Homework Problems #5

1. Define the following terms:

(a) Data Block

(b) BCC

(c) LRC

(d) Redundancy (what does it have to do with error detection?)

(e) Lateral Parity

(f) Longitudinal Parity

(g) Checksum

(h) Cyclic Redundancy Check

(i) Forward Error Correction (FEC)

(j) ACK

(k) NAK

2. What is the primary difference between an ERROR DETECTING and a

FORWARD ERROR DETECTING system?

3. What is the advantage of a 2's complement checksum over a standard
or "normal" checksum?

4. Calculate a normal 8-bit checksum for the following message:

"I THINK HOMER IS OK."

The Quote (") marks are NOT part of the data. Don't forget the blanks!

EXPRESS IN HEXADECIMAL. SHOW ALL WORK.

5. Repeat exercise 4, but use EVEN LONGITUDINAL PARITY; FORM AN 8-BIT BCC.

EXPRESS IN HEXADECIMAL. SHOW ALL WORK.

6. A CRC system has the following generator polynomial:

3

G(x) = X + X + 1

(a) How long will the BCC be, in bits?

(b) Calculate the BCC for data A5H.

(c) Calculate the BCC for data E7H.

ET270 Digital/Data Communications

Homework Problems #6

IBM 3270 PROTOCOL

1. Given: STANDARD SELECT

POLL LIST = { 4,1,3,2 }

HOST WANTS TO SAY "GO JUMP IN THE LAKE" TO TERMINAL #4

TERMINAL #1 HAS NOTHING TO SAY

TERMINAL #2 WANTS TO SAY "THANKS FOR THE LUNCH"

TERMINAL #3 HAS NOTHING TO SAY

TERMINAL #4 WANTS TO SAY "YOU'RE A MUD FARMER" TO THE HOST

Draw: An action diagram showing all messages that would be sent on the multi-drop network. Use "P" for Poll and "S" for Select.

Use a straightedge when making the diagram - draw neatly.

2. Two host systems are connected using 3270 on a point-to-point network. The following events are scheduled for each host:

KC HOST: EVENT @ 14:00. Three message blocks will need to be sent:

Block 1: "THIS IS LINE 1"

Block 2: "THIS IS LINE 2"

Block 3: "THIS IS THE LAST LINE"

LA HOST: EVENT @ 13:55. A single message block needs to be sent:

Block 1: "WE'RE SERIOUS ABOUT SUNGLASSES"