奔驰培训资料：光纤通讯 D2B 英文

1 Domestic Digital Bus (D2B) 507 HO D2B (ICC) 11-20-02 2 These technical training materials are current as of the date noted on the materials, and may be revised or updated without notice. Always check for revised or updated information. To help avoid personal injury to you or others, and to avoid damage to the vehicle on which you are working, you must always refer to the latest Mercedes-Benz Technical Publication and follow all pertinent instructions when testing, diagnosing or making repair. Illustrations and descriptions in this training reference are based on preliminary information and may not correspond to the final US version vehicles. Refer to the official introduction manual and WIS when available. Copyright Mercedes-Benz USA, LLC, 2002 Reproduction by any means or by any information storage and retrieval system or translation in whole or part is not permitted without written authorization from Mercedes-Benz USA, LLC or its successors. Published by Mercedes-Benz USA, LLC Printed in U. S.A. 3 What is D2B? The D2B acronym is derived from its definition as a “Domestic Digital Bus” D2B utilizes fiber optics to transmit data and control signals in the form of light The system is configured as a combination of an optical ring and a star topology (electrical start-up) 4 Transmission Medium (Core) Function: Carry optical signal Diameter: 1.0 mm Reflective Cladding Function: Contain light within core Protective Jacket Function: Protect cladding and core Diameter: 2.2 mm Color: Orange High speed: 5.6MB/sec (20MB/sec max) Light wavelength: 650 nanometers (red) Operating temperature: -40C to 85C Pros: Impervious to EMI / EMS Lightweight Improved signal quality Reduced electrical connections Cons: Fragile Repairs not possible without special equip D2B Fiber Optic Cable 5 Light passage through a slightly bent fiber: MINIMUM Radius = 25 mm Light passage through a stressed fiber: Light passage through a straight fiber: Handle With Care! 6 Fiber Optic Layout ? Always ensure that any ring construction follows a red-to- clear, clear-to-red logic ? Ensure that red is always on the chamfered side of the connector In-Line couplers follow the same logic as other ring connectors D2B Basic - Connection Configuration Maximum cable lengths - 0 couplers = 10m / 1 coupler = 7m / 2 couplers = 3.6m 7 h In order for the ring to function properly, the master MUST know the number of components on the ring and ORDER of those components with respect to the master. h Refer to the Service Information listed below for proper configuration: Date: August 2000 & September 2002 Document No.:SI 82.64/135 & S-B-82.64/135A Group:82 NOTE: Improper version coding and / or incorrect sequencing of components may result in intermittent and / or abnormal operation of the ring. D2B Basics - Version Coding 8 D2B Ring Configuration Optical Electrical COMAND D2B Master W220 shown What is the electrical for? The Fiber Optic Transceivers (FOTs) draw a large amount of current and therefore need to be put to sleep when ever the ring is not being used. An electrical wake-up signal is sent to all components on the ring to wake up the components. 9 Electrical Wake-up 0 12 ms v 100 ms approx. 5 3 High Low Undefined Electrical Wake-up COMAND D2B Master System Sequencing: ?Head unit issues wake-up pulse ?Connected components wake- up ?At the same time the electrical wake-up is issued, the head unit attempts to optically start the ring by issuing a series of ring start optical commands (max. of 4). 10 Electrical Wake-up 0 12 ms v 5 3 Electrical Wake-up (Open at CTEL 1) Open System Sequencing: Master issues wake-up pulse Connected components wake-up except CTEL1 Since CTEL1 cannot wake-up Three additional wake-up pulses are sent With each wake-up pulse a optical pulse was also issued COMAND D2B Master 4 optical pulses are sent but cannot transfer past CTEL 1 After the 4th pulse VR will issue a roll call pulse back to COMAND Ring lock cannot be established Ring shut down occurs 11 0 12 Division 100 ms v 5 3 Diagnostic Wake-up (500 ms) CD Changer (700ms) TeleAid 2 (900 ms) VR (1.1 s) Sound Amp. (1.3s) Telephone (1.5s) Diagnostic Wake-up (Normal) Optical ring must be open to do this test 12 0 12 Division 100 ms v 5 3 Diagnostic Wake-up (500 ms) CD Changer (700ms) TeleAid 2 (900 ms) VR (1.1 s) Sound Amp. Telephone (1.5s) Diagnostic Wake-up (With Fault) 13 Service TipService Tip Wake-up line is Z spliced on all models except 203 / 230 X30/8 Connector block connects all wake-up lines. Location: 203 = right front sill trough 230 = behind drivers seat under carpet 14 D2B Cable Damage KinkedPinched / Smashed ScrapedFractured / Cracked 15 D2B Network Tester Tester kit includes 2 units Measures the light received - checking optical cable - checking component output Can be used as a repeater 16 Switch unit ON All 3 LEDs should light once as a self-check. The “power” LED should then keep flashing green if battery OK. Remember to check both units! D2B Tester: Power ON check 17 Fiber test requires 2 testers Make sure switch is set correctly #1 #2 Tester #2 reads level Steady green= fiber OK Tester #1 transmits signal Checking Fiber Optic Cable 18 #1 #2 Red/green= marginal Red= fiber bad Checking Fiber Optic Cable 19 No illumination = no ring lock Next D2B componentPreceding D2B component Install tester in place of suspect component in D2B ring Check “level” signal Red flicker = signal weak Green flicker = OK D2B Component Substitution Test Note: to completely isolat