Campbell csi mAXON, Инструкция по эксплуатации

Страница: 26 / 74

Section 3. Radiotelemetry Network Components
3-4
3.1.6 RF310M Modem Communication Protocol
Comprehension of this section is not necessary for routine operation of the
RF310M Modem. The PC208W Datalogger Support Software accounts
for the necessary communication protocol.
There must be an RF310M Modem at both the calling (or computer) end of the
transmission link, and at the answer (or datalogger) end of the transmission
link. The modem at the calling end is the Start Of Link (SOL) modem, and the
modem at the answer end is the End Of Link (EOL) modem.
RF310M Modems must also be used at repeater stations. These RF310M
Modems are termed Middle Of Link (MOL) modems.
The RF310M Modem has five general modes of operation:
•
Wait Mode
•
Local Command Mode
•
Repeater Mode
•
End of Link Mode
•
Transparent Mode.
The RF310M is in the Wait Mode of operation when it is waiting to enter one
of the four other modes of operation. The Wait Mode is entered 1) after the
power-up sequence is completed, 2) following the "T" command when in the
Local Command Mode, and 3) when the system is reset by the Time-out Timer.
The Time-out Timer is a 60-second timer which is set every time a valid
transmission block is received on the RF link. The datalogger, being in
Telecommunications Mode, will override the Time-out Timer.
The Local Command Mode is used to set up and shut down an RF link. The
Local Command Mode is entered when the datalogger goes into
Telecommunications Mode after being in the Wait Mode. In this mode the
RF310M responds to command characters received on the Serial I/O port.
The RF310M is in the Transparent Mode after the RF link has been
established. In the Transparent Mode, any data received on the Serial I/O port
are organized into data blocks for transfer through the RF link.
The Repeater Mode is entered by MOL RF310M Modems. The function of
the Repeater Mode is to receive and then transmit data blocks. The signature of
each data block is checked before being sent to the next RF station. The block
is discarded if the signature of the data block is incorrect. The RF310M enters
the Repeater Mode when it receives a valid setup block that sets the RF310M
as a repeater.
The End Of Link Mode is entered when the RF310M receives a valid setup
block that sets the RF310M as the EOL modem. Upon entering the EOL
Mode, the RF310M brings the Serial I/O Ring line high which raises the
datalogger ME line, thus causing the RF310M to enter the Transparent Mode.
The Ring line is reset after the ME line comes high.