Campbell Scientific RF300-Series DRL VHF/UHF Radio Transceivers - Manual (Page 22)

SECTION 3. RADIOTELEMETRY NETWORK COMPONENTS
3-4
characters are summarized in Table 3-2. All
command characters must be capital letters.
TABLE 3-2. RF95A Command
Character Summary
Command Description
E Exit Link Command. The "E"
command causes the datalogger
to drop its ME line and shut
down the RF link.
F Fast Command. The "F"
Command is placed at the end
of the string of setup numbers.
In the RF95A-ME State, the
Serial I/O port of the EOL
modem will communicate with
the datalogger at 9600 baud with
the "F" Command. In the
RF95A-SDC State, the baud
rate from the computer to the
SOL modem will be 9600.
R Read Command. The "R"
Command reads back the
Shutdown Block.
S Link Setup Command. The Link
Setup Command is followed by
a string of setup numbers
representing the ID numbers of
the modems in the RF link.
T Terminate Command. The "T"
Command will reset the SOL
modem to the Wait Mode of
operation.
U Old Link Command. The "U"
Command will force RF
communication between radios
to 2400 baud rather than 3000
baud. DC95s purchased before
February 1989 can only be used
at 2400 baud. For further
information see Appendix F.
W Wait Command. The "W"
Command will force the RF
modem to wait until there is no
carrier detect before transmitting.
The first step in setting up an RF link, once in
the Local Command Mode, is to create a setup
block using the "S" command. The setup string
is entered via the computer as follows:
Sxxx yyy
where:
xxx = ID number of the RF95A which is
acting as the repeater in the link.
If no repeater is used then xxx is
omitted.
yyy = ID number of the EOL modem.
xxx and yyy are numbers from 1 to 255,
inclusive. The user can have up to 12 repeaters
in any RF link. Example 3-1 shows the setup
block for an RF link which will communicate
through three repeaters to an EOL modem, with
Station ID numbers of 10, 25, 50, and 30,
respectively. The Fast Command is used to
speed data transfer.
EXAMPLE 3-1. A Sample Setup Block
S10 25 50 30F
Notice that it is not necessary to include the
station ID of the SOL modem.
Press [ENTER] following the setup string of
station IDs to transmit the setup block. When
the RF link is established, a verification block is
sent from the EOL modem to the SOL modem.
Upon receiving this verification block, the SOL
modem and EOL modem have entered the
Transparent Mode of operation. At this point,
the dollar sign prompt "$" will be returned to the
computer screen. The datalogger connected to
the EOL modem is now in the
Telecommunications Mode and will respond to
the standard datalogger telecommunications
commands. If the verification block does not
return shortly, pressing [ENTER] will cause the
SOL modem to return to the Local Command
Mode.
3.1.7.2 Maintaining the RF Link
Data can be transferred once the RF link is
established. Data blocks are created and
transmitted by the SOL and EOL modems
according to the following two rules. First,
characters received on the Serial I/O port are
placed into data blocks of 238 characters each.
The block is then closed and transmitted. Any
remaining or new characters received at this
point are placed into a new data block. Second,
if during this loading process a delay of 290 ms