Publi s hed: 11-May-2011
Module Communications Network - Communications Network
Des cript ion and Operat ion
OVERVIEW
A number of different t ypes of communicati on network are incorporated into the vehicle wiring harnes s es for t het ransmis s ion of commands and informat ion between control modul es. The confi gurati on ins tal led on a parti cul ar vehicl edepends on t he model and equi pment level .
The communicati on net works avail abl e on t he vehi cl e are:
Local Int erconnect Network (LIN) busMedium speed Controll er Area Network (CAN) busHigh speed CAN busMedia O rient ated Sys tem Trans port (MO ST) ring
BusBaud Rate
LIN bus9.6 kbit s /s
Medium s peed CAN bus125 kbi ts /sHi gh Speed CAN bus500 kbi ts /s
MOST ring24 Mbit s/s
LOCAL INTERCONNECT NETWORK BUS
The Local Int erconnect Network (LIN) bus is a low s peed broadcas t net work that employs mas ter and s lave component s .The mas ter component t rans mit s a mess age along a si ngle wi re to the s lave component s i dent ifyi ng which s lave i s t ores pond. The mes s age has a header (s lave ident ifi er) and an empt y data fi eld. The identi fi ed s lave component fi ll s thedata fiel d wi th t he relevant i nformat ion and ret urns a mes s age to the mast er component along t he s ame wire.
CONTROLLER AREA NETWORK BUS
The Control ler Area Network (CAN) bus i s a high speed broadcast net work where cont rol modules aut omat icall y t rans mitinformat ion every few micros econds . Informati on is broadcas t down a pair of t wis t ed wires, known as 'CAN high' and 'CANlow'. Informat ion i s transmit ted on t he CAN bus as a vol tage di fference bet ween t he 2 wi res .
Two CAN bus net works are used on the vehicle; medi um s peed and high s peed, wi th the Cent ral Juncti on Box (CJB) acti ngas a gat eway bet ween t he 2 networks . The t abl e below shows t he wi re colors us ed on both net works .
Netw orkHighLow
Medium SpeedGrey and orangeViol et and orange
Hi gh SpeedW hit e and bl ueW hi te
MEDIA ORIENTATED SYSTEM TRANSPORT (MOST) RING
The Media O rient ated Sys tem Trans port (MO ST) ring us es fiber opt ic cables t o t rans port data and audio s ignal s around t heinformat ion and ent ertai nment sys tem. The fiber opti c cabl es are arranged in a ri ng, wit h each uni t on t he ri ng havi ng a'MOST in' and 'MOST out ' connect ion.
The MOST ring i s a s ynchronous net work. A t imi ng mas ter s uppl ies t he clock and all ot her component s on t he ri ngs ynchronize t heir operat ion t o t hi s clock. The t iming mas t er for the MOST ri ng is the i ntegrat ed cont rol module.
W hen handli ng MOST fiber opt ic cables t he fol lowi ng precaut ions s houl d be obs erved:
Aft er dis connect ion of any cables careful ly i nst all appropri ate dus t caps to protect the mati ng faces of theconnectors from damage and contami nat ion.Avoi d i nt roducing bends of les s t han 25 mm (0.98 inches ) radi us or ki nks int o the fiber opti c cabl e duri ng s ervice orrepair. Tight bends or kinks could i mpair operat ion, caus e immediate s ys t em failure, or future s ys t em fail ure.Avoi d exces s ive force, st rai n or s tress on the fibers or connect ors es peci ally permanent st res s after rei nst all at ion.
Ring Break Diag nostics
Incorporat ed i nt o t he Auxili ary Junct ion Box (AJB) is a Ri ng Break Di agnos ti cs (RBD) l ink. The RBD li nk hous es a copper linkwhich when removed init iat es the ri ng break diagnost ics mode. The ri ng break di agnosti cs mode allows the t echni ci an tolocate an opt ical fi ber break in t he MOST ring. To i nit iate the ring break diagnos t ics mode, carry out t he fol lowi ng proces s :
Connect t he Land Rover approved di agnos ti c s yst em.Ensure t he vehi cl e is in power mode 4 or great er.Remove the RBD li nk for t he length of ti me s peci fi ed by the Land Rover approved di agnos ti c s ys t em.Replace the RBD li nk.
Aft er approxi matel y 30 s econds a Di agnos t ic Trouble Code (DTC) wi ll be logged i n the Int egrated Cont rol Modul e,identi fyi ng the l ocat ion of t he faul t. The DTC can be read and int errogat ed usi ng t he Land Rover approved di agnos ti cs ys t em.
CONTROL DIAGRAM - LIN BUS (SHEET 1 OF 2)
• NOTE: O = LIN bus
