Operations Manual

OPERATIONS 4-33
O&M of the MCC-545B PACKET DATA RADIO
12/2000
default destination assignment for their routing destination(s). This destination is specified using
the DESTINATION command:
DESTINATION,OFF Causes error in text message entry, data reports print
locally and are not transmitted.
DESTINATION,0 Specifies source routing (see paragraph 4.8.3.1)
DESTINATION,1 Special Base to Host routing (see paragraph 4.8.3.2)
DESTINATION,D1,D2,D3,D4 Up to 4 destinations can be given
Data reports which use the MCC-550 type of sensor report formats have no bits within the
transmitted frame to specify where the report is to be routed or who originated the data. This
condition is not an oversight; it is designed that way to be compatible with the older format that
is optimized for minimum overhead. If data reports must be forwarded to multiple destinations,
they are sent on by the Master using message format; an exception to this rule occurs when the
Master is using a substitution table (SUBST command), in which case, the proper ID is
substituted according to the table and sent on as though originated at that node.
Position reports sent on to multiple destinations are sent as multiple reports, each containing a
single destination ID. Text messages, packet protocol data, remote commands and remote
command responses all contain fields for source and destination addresses.
When MCC-550 type sensor frames are received by a Master, the assumption is that the
originator is the Remote that transmitted the data frame and that the DESTINATION is 0 (i.e.,
source routing). Sensor data reports and position reports are transmitted from the originating
unit in the shortest possible format with minimum overhead. This approach provides the best
throughput in meteor burst networks where the Remote has a MB Master. In LOS networks this
criterion is not as critical but all extra bits transmitted contribute to wasting system capacity. In
networks where the message or data must be transmitted multiple hops, the longer message
format must be used because the relay units are not the originating unit and the origination ID
and destination ID must be contained in the message.
4.8.4 Source and Group Routing
Data with no destination and text messages with “0” being the destination can be routed by a
Master Station that has a source routing table. This table gives a list of destinations for each
data-source Remote. A 520B/C can load this table from its 520B.INI file; whereas, the 545B can
only support one table entry that is given in the SOURCE RELAY, ID command. If the
Master’s ID is in the table for the source of the data report being received, the Master has no
table or there is no entry for the source Remote, the Master will print the report on the MNT,
DTA, and ALT ports for delivery to the Host Computer. The LINK, DEST, SOURCE,
SOURCE, SOURCE, command is used to build the table in the 520B/C Master, for example:
LINK,1000,1200,1201,1202,1203
LINK,1001,1300,1301,1302