Instruction manual

SECTION 8. FILES, PROTOCOLS, AND UTILITIES
8-3
• StationName Space TableName Space
Beginning Space End Space Flag.
• StationName and TableName limited to 8
characters.
• Space is the ASCII space character.
• Beginning is the beginning time stamp or
record number.
• End is the ending time stamp or record
number.
• Flag is a 0 or 1.
• Flag of 0 Indicates beginning and end are
Record Numbers.
• Flag of 1 Indicates beginning and end are
time stamps.
• Time stamps are represented as the number
of seconds since midnight January 1, 1990.
8.4 RADIO TEST RESULTS
Completed link test results are shown in the "Test
Status/Results" box. If successful, test results
show the PROM signature of the RF modem
whose switch setting is last in the RF path, and a
communication "Quality Report" with a record for
each hop specified in the path. The number of
"Quality Records" reported in the test response
depends on the number of RF modems listed in
the RF path. If one remote node is listed in the
command then there will be two quality records.
The first record shows how well the remote node
was able to receive from the base, the second
shows how well the base was able to receive from
the remote. With two or more modems listed in
the path, the first quality record will indicate how
well the most remote modem received. The rest
of the quality records show how well data was
received with each hop going from the most
remote node back to the base. So, if two RF
modems were listed in the test path, there would
be three quality records in the response. The
second quality record would apply to how well the
repeater received from the remote, and the third
record would apply to how well the base received
from the repeater.
A "Quality Record" is made up of five values as
follows:
First Value test packet size;
Second Value front of 2T envelop;
Third Value back of 2T envelop;
Fourth Value front of 1T envelop;
Fifth Value back of 1T envelop.
The "test packet size" is usually around 238, but
varies a little depending on network layout. This
value will be half or less of the expected 238 if
packets are being lost for one reason or
another. For example, if packets are being
walked on by outside RF activity, the test packet
will not make it though and will be retransmitted
at a smaller size. Over RF, data is transferred
as a stream of bits encoded into short and long
periods of time between transitions. We call the
short time a "1T" period and the longer a "2T"
period. Each transition is expected to fall within
a certain window of tolerance to be valid. If
there is too much error in the signal and the
transition falls outside its allotted window, the
packet will be in error and be retried. As a
packet is received the RF95T keeps track of the
transition that occurred closest to the front of
the allowable window and closest to the back.
These values are kept for both the 2T and 1T
windows and are the last four values of the
"Quality Record". Both windows are 204 ticks
long, so if the transmission was perfect, the
data envelope front and back would both be
close to 102. The closer the front value gets to
0 and the closer the back value gets to 204, the
worse the quality.
8.5 CSI LOGGER DATA EXPORT
PROTOCOL
The CSI Logger Data Export Protocol (LDEP) is
used on top of network transfer protocols such as
OS/2 Named Pipes and TCP/IP Berkeley Sockets
to transfer datalogger measurement records from
one computer (or process) to another. The
computer responsible for collecting data from the
datalogger network (the server) will make a pipe
or socket connection available. The computer
that receives data (the client) must connect to the
provided pipe or socket to receive data.
The server has the responsibility to see that every
collectable record is collected from the network of
dataloggers. To ensure that all of these records
are transferred to the client, LDEP will make use of
an acknowledgment scheme. The basic idea
behind the protocol is that as each record is sent
to the client, the client will report the Station Name,
Table Name, and Record Number back to the
server after it has secured that record. The server
will use the acknowledgment to mark the progress
of the transfer. When the session is broken, the
server will buffer unacknowledged records until the
connection is re-established. The server will
maintain transfer progress information on disk so
that if the server goes down, it can recover and
continue to transfer all collectable records.