User's Manual

MDS 05-6302A01, Rev. B MDS Mercury 16E Technical Manual 23
The transceiver keeps a TCP session open until internal timers that
monitor traffic expire. Once a TCP session is closed, it must be opened
again before traffic can flow. The timeout period, labeled TCP Keepalive,
is user-configurable and should be set to match the application data flow
and balance a trade-off between responsiveness and connection
overhead. TCP connection establishment can introduce a slight delay to
data delivery, as it performs handshaking between the client and server.
On the other hand, leaving a session open can waste bandwidth due to
session management packets.
UDP Multicast IP addressing provides a way to do a limited broadcast to a specific
group of devices. This is known as “multicast addressing.” Many IP
routers and switches support this functionality. Multicast addressing
requires the use of a specific set of IP addresses set apart by the Internet
Assigned Numbers Authority (IANA). UDP multicast is generally used
to transport polling protocols used in SCADA applications where
multiple remote devices will receive and process the same poll message.
As part of the multicast implementation, the radio sends IGMP
membership reports, IGMP queries, and responds to membership
queries. It defaults to V2 membership reports, but responds to both V1
and V2 queries.
The Multicast Mode parameter on the transceiver must be set
appropriately in order for the transceiver to receive multicast traffic.
Setting the Multicast Mode parameter causes the transceiver to join the
multicast group.
Data Buffering The Buffer Size and Inter-packet Delay parameters are user-configurable.
They work together to determine how many bytes are captured in a
single packet. When a number of bytes equal to the Buffer Size are
received from the serial port, those bytes are encapsulated and sent as a
TCP or UDP packet. If a delay equal to the Inter-packet Delay is
experienced after some number of bytes, then the bytes received up to
the delay are encapsulated and sent as a TCP or UDP packet.
Setup Wizard The Serial Wizard handles configuration of the serial port. To access the
Serial Wizard, navigate to the
Setup Wizards link on the left sidebar. The
Setup Wizard - Serial Configuration page appears.