electrical circuit part B

Question 1

what are the two main advantages to multiplexing

Answer 1

40% less wires connectors and fuses . allows technicians to view and record data streams

Question 2

what is multiplexing

Answer 2

the ability to send and receive digital and electronic signals over a pair of wires at high speed

Question 3

what are the three multiplexing protocols

Answer 3

J1587/J1708
J1939 / CAN
ISO 11783 /CAN

Question 4

who controls the protocol and rules that a device must follow in order to communicate with other modules

Answer 4

SAE

Question 5

what determines the priority of a massage

Answer 5

a priority code embedded in each message

Question 6

when removing a bulkhead connector you must remove

Answer 6

both locks primary and secondary locks

Question 7

what does the ISO stand for and what do they do

Answer 7

International Organization Standardization . implement international proprietary , industrial and commercial standards

Question 8

baud rate

Answer 8

the speed of data transfer over a network measured in kilo bytes per second

Question 9

back bone

Answer 9

is a networks method of connection . ( fiber optics ,wires twisted pairs )

Question 10

what is another name for the backbone

Answer 10

data bus

Question 11

stub

Answer 11

is a section of data link that branches off the back bone and connects each node

Question 12

what is the maximum length a stub can be

Answer 12

one meter

Question 13

another name for a stub

Answer 13

a branch

Question 14

node

Answer 14

is a computer or other device that has a unique address

Question 15

terminating resistor

Answer 15

a resistor placed at each end of a data link to eliminate electrical interference ( 120 ohms resistor )

Question 16

standing waves

Answer 16

are electrical reflections or waves that can cause major problems with module communication

Question 17

vehicle communication data bus

Answer 17

is the communication network that connects all of the multiplexed components on a piece of mobile equipment

Question 18

protocol

Answer 18

is a common language for data communication between control modules

Question 19

controller area network (CAN)

Answer 19

is a communication protocol used on highway trucks

Question 20

what is the baud rate of J1939

Answer 20

250 kb/s

Question 21

where is the drain wire in shielded twisted pair connected

Answer 21

to ground

Question 22

why are conductors twisted

Answer 22

helps provide immunity to magnetic fields . allows conductors to maintain a constant capacitance

Question 23

what is the twist rate per foot in a twisted pair to provide sufficient resistance to electromagnetic force

Answer 23

12 twists per foot

Question 24

most modern data bus configuration use

Answer 24

linear topology . ( main backbone with stubs )

Question 25

why does the J1587 / J1708 not need terminating resistor

Answer 25

because of the slow communication rate 9600 baud or 9.6 kb/s

Question 26

why are messages used over J1587 / J1708 used only for diagnostic purposes

Answer 26

because of the slow communication speed limits the amount of nodes on the datalink and the information contained in each message to a maximum of 21 bytes

Question 27

message identifier

Answer 27

MID is one byte long ( 8 bits ) and indicates the source address of the transmitting node

Question 28

parameter identifier

Answer 28

PID is usually one byte long ( 8 bits ) and indicates what parameter the following data corresponds

Question 29

FMI

Answer 29

fault mode indicator . indicates the type of fault the system is having

Question 30

checksum

Answer 30

the checksum follows the final byte of data . it is one byte long and completes the message . if the message checksum value is zero then the message is valid

Question 31

why must the interconnector pins of J1587 be gold plated

Answer 31

to reduce the possibility of resistance

Question 32

what color are the J1587 / J1708 twisted pair

Answer 32

orange and white

Question 33

on most OEM 9 pin connectors what pin is the ground pin

Answer 33

the center pin

Question 34

what is one of the first test preformed with all multiplexing systems

Answer 34

see if the system is receiving power

Question 35

if you obtain a low voltage or no voltage reading on a data wire test

Answer 35

one of the circuits may be shorted out corrupting the entire data bus

Question 36

SAE J1939 PGN

Answer 36

parameter group number . is usually 8 bytes long and its purpose is to identify the message and its data

Question 37

SAE J1939 SPN

Answer 37

suspect parameter number . identifies and reports where a failure has occurred

Question 38

SAE J1939 FMI

Answer 38

is a five bit number and defines 0 to 31 types of failure

Question 39

SAE J1939 twisted pair wires

Answer 39

are green and yellow

Question 40

what is the non insulated copper wire on the shielded twisted pair

Answer 40

drain wire used to prevent signals from radiating out and blocks outside electromagnetic interference from corrupting the signal

Question 41

in a J1939 system a total loss of communication usually indicates

Answer 41

a voltage or hardware porblem

Question 42

in a J1939 system a partial loss of communication usually indicates

Answer 42

a data bus device failure