ISO 14230-2:2013 pdf free.Road vehicles—Diagnostic communication over K-Line (DoK-Line)—Part 2: Data link layer.
7 Data link layer overview
7.1 General
This part of ISO 14230 specifies the data link layer services which are used in client-server based systems to transmit data from one to the other entity. The client, referred to as the external test equipment, uses the data link layer services to transfer diagnostic request data to one or more servers, referred to as an ECU. The server, usually a function that is part of an ECU, uses the data link layer services to send response data, provided by the requested diagnostic service, back to the client. The client is usually the external test equipment but can in some systems also be an on-board test equipment. The usage of data link layer services is independent from the external test equipment being an off-board or on-board test equipment. It is possible to have more than one client (test equipment) in the same vehicle system.
In order to describe the function of the data link layer, services provided to higher layers and the internal operation of the data link layer have to be considered.
7.4 Specification of DoK-Line data link layer service primitives
7.4.1 DL _Data.request The service primitive requests transmission of < MessageData > with < Length > bytes from the sender to the receiver peer entities identified by the address information in SA and TA. Each time the DL_ Data.request service is called, the data link layer shall signal the completion (or failure) of the message transmission to the service user by means of issuing a DL_ Data.confirm service call.
7.4.2 DL .Data.confirm
The data link layer issues the DL. .Data.confirm service. The service primitive confirms the completion of a DL. Data.request service identified by the address information in SA and TA. The parameter < Result_ DoK-Line > provides the status of the service request.
There is no address information contained in the indication, because the first byte only indicates the start of a message. There can only be one message transmitted on the data link layer at a time (no multiple messages can be pending in the data link layer at a time); therefore, the first byte indication does not require any address information. The final indication of the message reception will contain the address information for the received message.
7.4.4 DL ,Data.indication
The data link layer issues the DL_ Data.indication service. The service primitive indicates < Result. _DoK- Line > events and delivers < MessageData > with < Length > bytes received from a peer protocol entity identified by the address information in SA and TA to the adjacent upper layer. The parameters < MessageData > and < Length> are only valid if < Result_ DoK-Line > equals DoK-Line_ 0K.
8.3.3.3 Initialization sequence of FAST_ INIT according to ISO 14230-2
The transfer of a wake-up pattern WuP as described above is followed by a StartCommunication request message from the client (external test equipment) and a response message from the server (ECU]. The first message of a fast initialization always uses a header with target and source address and without additional length byte. A server ( ECU) may answer back with or without address information and length byte and tells its supported modes within the key bytes. The pattern begins with a falling edge after an idle time on K-line. While communication is running, it is not necessary for a server (ECU] to react when receiving a wake-up pattern WuP.
8.3.3.4 Message sequence of FAST INIT according to ISO 14230-2
ISO 14230-2 FAST INIT begins with the WuP transmitted by the client to the vehicle that is 50 ms long. This pattern is followed immediately by a StartCommunication request message from the client to the vehicle. The vehicle should then respond to the external test equipment with a StartCommunication response message, including a pair of key bytes.
The StartCommunication request message comprises a format byte, target address byte, source address byte, and a service identifier byte of 0x81.ISO 14230-2 pdf download.