Campbell Scientific RF310, RF312, RF313 Narrowband Radios - Manual (Page 29)

Section 3. Radiotelemetry Network Components
3-7
3.1.7.3 Shutting Down the RF Link
Sending the "E" character to a datalogger causes the datalogger to drop its ME
line, which causes a shutdown of the RF link.
A shutdown block is created by the EOL modem which can be sent to the
computer as an indicator of communication quality. The shutdown block
consists of three RF Link Quality Accumulators (RLQA). Each RF310M in the
link will have three RLQAs which are appended to the shutdown block. The
RLQA from each RF310M are representative of the active period of the link.
The first three RLQAs represent the EOL modem connected to the datalogger,
the following sets of numbers will be for any MOL modems (in order of
occurrence from the EOL modem), and last will be the SOL modem. A
description of the shutdown block is contained in Table 3-3.
TABLE 3-3. Summary of the Shutdown Block
xxxx yyyy zzzz
xxxx = Number of communication failures.
yyyy = Noise level indicator.
zzzz = Noise level indicator.
A communication failure occurs when a signature of a block of data doesn't
match its original signature. These blocks are subsequently retransmitted. The
noise level indicators should be 102 (±70) at the standard 3.0K baud rate, or
124 (±70) at 2.4K baud.
The noise level indicators are reset and subsequently become active in the
respective EOL and SOL modems as the Transparent Mode is entered
(immediately after setup). The MOL modems are reset and become active
when the setup block is propagated to the next station in the RF link.
After the "E" character is received by the datalogger a CR-LF is sent through
the RF link to the SOL modem. The shutdown block follows after a one second
delay. When the shutdown block is received and verified the SOL modem will
leave the Transparent Mode and re-enter the Local Command Mode, indicated
by sending an exclamation point (!) to the computer.
The shutdown block can be viewed by sending the "R" command. Example 3-2
illustrates a shutdown block for three RF95s.
EXAMPLE 3-2. Sample Shutdown Block
!R
EOL modem - > 0004 0110 0097
MOL modem - > 0002 0108 0090
SOL modem - > 0000 0105 0093
!
The first line of numbers, which are the first three RLQAs, represent the EOL
modem. The second line represents a MOL modem, and last is the RLQAs for
the SOL modem. The 0004 indicates that four interruptions occurred on the
EOL modem while the link was active. Interruptions are non-data blocks such