9XTend-PKG-U™ USB RF Modem User’s Guide
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4.1. Addressing
Each RF packet contains addressing information that is used to filter incoming RF data. Receiving
modules inspect the Hopping Channel (HP parameter), Vendor Identification Number (ID parame-
ter) and Destination Address (DT parameter) contained in each RF packet. Data that does not pass
through all three network security layers is discarded.
Figure 4-01. Addressing layers contained in the RF packet header
4.1.1. Address Recognition
Transmissions can be addressed to a specific modem or group of modems using the DT (Destina-
tion Address) and MK (Address Mask) commands. A receiving modem will only accept a packet if it
determines the packet is addressed to it, either as a global or local packet. The receiving modem
makes this determination by inspecting the destination address of the packet and comparing it to
its own address and address mask [refer to the figure below].
Figure 4-02. Address Recognition (@ the Receiving RF Modem)
TX_DT = Destination Address of transmitting modem
RX_DT = Destination Address of receiving modem
RX_MK = Address Mask of receiving modem
RX_MY = Source Address of receiving modem
The transmitting modem determines whether the packet is intended for a specific node (local
address) or multiple nodes (global address) by comparing the packet's destination address (DT)
and its own address mask (MK) [refer to the figure below]. It is assumed that the address masks
on the transmitting modem and receiving modem have been programmed to the same value for
proper operation in each RF Communication Mode.
Figure 4-03. Address Recognition (@ the Transmitting RF Modem)
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