User's Manual

TS4000 Radio Modem User’s Manual AirNet Packet Protocol 26
Control Description
Enable Multicast
Reception
This control enables the multicast capability of the modem
and also enables the entry of multicast groups.
Multicast Groups This control is a list of multicast addresses. These
addresses have the same range as the group addresses.
The user can use as few or as many (up to the list size)
multicast groups as desired.
By default, a modem accepts two kinds of broadcasts.
!
Network broadcasts are received by all modems.
!
Group broadcasts are received by modems with the same group address as
the transmitting modem.
Control Description
Max Retries This control sets the maximum number of transmit retries.
A retry is attempted if a packet is sent and an acknowledge
is not received within the time defined by the packet timeout
control. After the maximum number of retries have been
attempted the packet is cleared from the transmit buffer.
Retries do not apply to any kind of broadcast transfers or
individual transfers without acknowledgment.
Max Packet Size This control defines the maximum packet size in bytes. Any
burst that is larger than this number of bytes will be broken
up into multiple packets with this maximum packet size.
Note that there is a difference between bytes and
asynchronous characters. A byte is always eight bits of
data. The number of bits in an asynchronous character is
dependent on the setting of the asynchronous character
control fields.
Packet Timeout The packet timeout is the amount of time the modem waits
for an acknowledgment before re-sending a packet (see
Network Setup - Setting Packet Timeout).
This field selects the type of transfer that the modem defaults to at power up.
This will remain as the transfer type until it is switched using the appropriate
control string.
Selection Description
Individual Transfer This is a standard point to point data transfer with
acknowledgments.
Individual Transfer
w/o Acknowledge
This is a point to point data transfer but without any
acknowledgments. This implies that there are no transmit
retries if the packet is received with errors.
Group Broadcast This is a broadcast to a group of modems. Receiving
modems will accept two types of group broadcasts.
!
Group broadcasts - Broadcasts where the destination
group matches the receiving modem's group.
!
Multicast broadcasts - Broadcasts where the
destination group matches a group from the receive
modem's multicast group list. For these broadcasts to
be received, the receiving modem must have multicast
reception enabled.
Network Broadcast This is a broadcast to all modems.
Packet Operation
Default Transfer