Prior to being able to exchange Messages, the HHT and Communications Hub shall undertake the following steps:
the HHT shall identify the Communications Hub and initiate the CBKE process using Inter-PAN Communications, as specified in the ZSE specification;
the Communications Hub shall not respond to any such request if more than 60 minutes has elapsed since the Communications Hub’s most recent power on, or if there is a Device of type HHT already in the CHF’s Device Log. Otherwise, the Communications Hub shall respond to the CBKE request;
if CBKE does not succeed, processing shall cease. Otherwise, processing shall continue from step 49;
using the APS link key established through CBKE to secure the commands:
the HHT shall send a RequestTunnel command to the Communications Hub, with contents as per Section 10.2.2;
the Communications Hub shall send a RequestTunnelResponse command in response;
if TunnelStatus in the response is not 0x00 (‘success’), processing by the HHT shall cease. Otherwise the HHT shall send a TransferData command with the TunnelID parameter set to the TunnelID provided in the RequestTunnelResponsecommand and the Data parameter payload set to the concatenation:
Entity Identifier of the HHT || 16 octet Install Code of the HHT
on receipt of the TransferData command, the Communications Hub shall:
add the HHT’s Entity Identifier to the CHF Device log, recording the Device as being of type HHT, so with a device_type of 0x7E with its DLMS COSEM class_id 104 meaning;
permit joining of the SMHAN for either (1) 240 seconds or (2) until the HHT has joined the SMHAN, whichever is the earlier; and
start a timer. When that timer reaches 0xFFFF seconds, the CHF shall remove the HHT from its Device Log, remove the HHT from the SMHAN and close any open tunnels to the HHT.
having added the HHT to its Device Log, the CHF shall send a Default Response to the HHT and close the tunnel to the HHT;
on receipt of the Default Response, the HHT shall, if that Default Response contains a Status Code of 0x00 (‘success’), attempt to join the SMHAN;
if the joining is successful, the HHT shall send a RequestTunnel command to the CHF, with contents as per Section 10.2.2;
the CHF shall process the RequestTunnelcommand and send a RequestTunnelResponse command in response;
if TunnelStatus in the RequestTunnelResponse command is not 0x00 (‘success’), processing by the HHT shall cease. Otherwise the HHT and CHF may now exchange Messages using the TransferData command.
Note that steps 1 to 4.j above use Inter-PAN Communications; the remaining steps use the standard ZigBee SMHAN communications.
Once the HHT has joined the SMHAN, any Messages received by the CHF from the HHT in the Data parameter payload of a TransferData command, shall be forwarded to the relevant Device on the SMHAN as if they were received via the Communications Hub’s WAN interface.
Whilst the HHT is in the CHF’s Device Log and joined to the SMHAN, any Responses received by the CHF from any SMHAN Device shall be provided to the HHT using the TransferData command. Such Responses shall also be sent over the Communications Hub’s WAN interface, if available.
Once the HHT usage on the SMHAN is complete, the HHT should send a CloseTunnel command to the Communications Hub. On receipt of such a CloseTunnel command from an HHT, the Communications Hub shall process that command as per the ZSE specification and shall: