Commission Implementing Regulation (EU) 2016/799 of 18 March 2016 implementing Regulation (EU) No 165/2014 of the European Parliament and of the Council laying down the requirements for the construction, testing, installation, operation and repair of tachographs and their components (Text with EEA relevance) (c. 799)

ANNEX I C U.K. Requirements for construction, testing, installation, and inspection

Appendix 14

REMOTE COMMUNICATION FUNCTION U.K.

5. REMOTE COMMUNICATION DESIGN AND PROTOCOLS U.K.

5.4 DSRC Protocol requirements for RTM U.K.

5.4.1 Overview U.K.

DSC_34 The transaction protocol to download the Data across the 5.8 GHz DSRC interface link shall be according to the following steps. This section describes a transaction flow under ideal conditions without retransmissions or communication interrupts. U.K.

NOTE The purpose of the initialisation phase (Step 1) is to set up the communication between the REDCR and DSRC-VUs that have entered the 5.8 GHz DSRC (master-slave) transaction zone but have not yet established communication with the REDCR, and to notify the application processes. U.K.

— Step 1

Initialisation. The REDCR sends a frame containing a ‘beacon service table’ (BST) that includes the application identifiers (AIDs) in the service list that it supports. In the RTM application this will simply be the service with the AID value = 2 (Freight&Fleet). The DSRC-VU evaluates the received BST, and shall respond (see below) with the list of the supported applications within the Freight&Fleet domain, or shall not respond if none are supported. If the REDCR does not offer AID=2, the DSRC-VU shall not answer to the REDCR.

— Step 2

The DSRC-VU sends a frame containing a request for a private window allocation.

— Step 3

The REDCR sends a frame containing a private window allocation.

— Step 4

The DSRC-VU uses the allocated private window to send a frame containing its vehicle service table (VST). This VST includes a list of all the different application instantiations that this DSRC-VU supports in the framework of AID=2. The different instantiations shall be identified by means of uniquely generated EIDs, each associated with an Application Context Mark parameter value indicating the application and standard supported.

— Step 5

Next the REDCR analyses the offered VST, and either terminates the connection (RELEASE) since it is not interested in anything the VST has to offer (i.e. it is receiving a VST from a DSRC-VU that is not supporting the RTM transaction), or, if it receives an appropriate VST it starts an app instantiation.

— Step 6

To bring this about, the REDCR shall send a frame containing a command to retrieve the RTM data, identifying the RTM application instantiation by specifying the identifier corresponding to the RTM application instantiation (as specified by the DSRC-VU in the VST), and shall allocate a private window.

— Step 7

The DSRC-VU uses the newly allocated private window to send a frame that contains the addressed identifier corresponding to the RTM application instantiation as provided in the VST, followed by the attribute RtmData (payload element + security element).

— Step 8

If there are multiple services requested, the value ‘n’ is changed to the next service reference number and the process repeated.

— Step 9

The REDCR confirms receipt of the data by sending a frame containing a RELEASE command to the DSRC-VU to terminate the session OR if it has failed to validate a successful receipt of the LDPU goes back to step 6.

See Figure 14.6 for a pictorial description of the transaction protocol.