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26.3.2 Diagnostic Communication > On-Board Diagnostics II - Pg. 662

662 CHAPTER 26 Cyber-Physical Security of Automotive Information Technology vehicles. OBD-II, which is the successor of OBD-I is currently the most widely used. The Soci- ety of Automotive Engineers (SAE) International defines standard specification of OBD-II in [25] and [26], which encompasses, ­ ­ ­ ­ ­ ­ or other embedded systems, automotive ECUs should be up-to-date, and modified when they have software faults. Software runs on personal computers can be remotely modified at any time through Internet. However, vehicles are not usually connected to Internet. This poor con- nectivity makes ECU suppliers prefer off-line programming at end-customer mechanic shops. For this reason, most ECUs use flash mem- ory to store their software, which makes them reprogrammable. Another reason that ECU companies pre- fer reprogramming via in-vehicular network is the end of line programming (EoLP). Design- ing many variants, building production lines for them, managing multiple inventories cost much more than a single product. On the other hand, while sharing the same software and hardware platform between different variants of ECUs requires reprogramming, it does reduce cost. Therefore, many ECU companies design and pro- duce ECUs using a common platform for all vari- ants. Automobile companies then assemble ECUs using the same production line for all variants, and just reprogram each variant as necessary at the end of their product line. Reprogramming is done using diagnostic networks for outside access. To reprogram ECUs, the on-board diagnostics II (OBD-II) interface is widely used because the interface is easy to access, and directly connected to in-vehicular network. Most auto mechanic shops have standard equipment to access ECUs via OBD-II. Physical characteristics of diagnostic connec- tor and its pinout definitions; Electrical characteristics; Signal formats; Communication layers; Message formats of data link layer; Application circuits for the communication. The OBD-II standard can support five differ- ent communication protocols. ­ ­ ­ ­ ­ SAE J1850 PWM [26] SAE J1850 VPW [26] ISO 9141-2 [27] ISO 14230 keyword protocol 2000 (KWP 2000) [28] ISO 15765 CAN [29][30][30][32][33] 26.3.2. Diagnostic Communication Modern vehicles exploit several different net- works [24] to support a variety of automo- tive embedded systems. Each ECU can access the other ECUs or be diagnosed from out- side by exploiting these networks. Among them, five representative networks can be accessed via OBD-II interface. On-Board Diagnostics II. The OBD system has been developed to provide car owners and engi- neers with accessibility to various networks in ISO-9141-2 and ISO14230 KWP2000 are based on LIN. LIN provides easy ways to access. The network can be accessed through RS-232C serial ports on personal computers with K-line transceiver. The schematics of LIN interface cir- cuit are readily available on the Internet [34] and cost to implement is a mere $10. Though CAN transceivers are difficult to build, CAN buses are easily accessed by hackers using a CAN probe interface on their personal computer. All OBD-II pinouts use the same connector but are used selectively for each vehicle model. Fig- ure 26-5 shows these pinouts. Table 26-4 shows the signal definitions of the OBD-II connectors defined by SAE J1962. Local Interconnect Network exploits conven- tional low-cost universal asynchronous receiver 1 9 8 16 FIGURE 26-5 J1962 OBD-II connector.