Specifications

HYDROLOGICAL SERVICES
DL3 100-012 IMP
Issue 2: 15/11/2005
is powered before a measurement is made. The "River Increment" (RVI) parameter defines the
river height recording increment resolution expressed in millimetres. The "River Height Reference"
(RVHR) is an offset that is added to the river height as measured by the transducer alone. See
section 4.1.12. for more information on these commands.
Three separate "River Alarms" (RVAL1, RVAL2, RVAL3) may be programmed in a logger that
has a communication path to a computer. An alarm will cause the logger to perform a certain
sequence (defined by the CALL, CALL NUMBER, and CLEAR parameters) that will dial out
through a modem to a computer and send a river request message. River alarm 1 and 2 (RVAL1,
RVAL2) are threshold alarms that are triggered when the river height exceeds the RVAL1 or
RVAL2 parameters. Rainfall alarm 3 (RVAL3) is a rate of river change alarm that monitors the
rise or fall of a river in a defined period. Note that the master alarm flag must be enabled (AL=on)
before alarm checking is performed. See section 4.1.2. for more information on these commands.
3.2.6 Communications
The logger has an RS232 serial interface to support asynchronous ASCII communications to
accommodate data extraction and user set-up. This port operates at 300, 1200, and9600 baud with
either no parity, 8 data bits and 1 stop bit or evenparity, 7 data bits and 1 stop bit selectable via dip
switches. The communication port supports software flow control, Xon/Xoff protocol and the
standard RS232 handshake and control signals. The communication sequence to a modem can be
customised by use of the CALL and CLEAR sequences. See section 4.1.5.
Message transmission may be initiated from the logger by an automatic calling feature (see the
"SEND" command in section 4.1.6) or via preset rain and river alarms (RALx, RVALx) or via a
user polling sequence. Several destinations may be automatically called by using the programmable
callnumbers (CN1, CN2, CN3). If a destinationis "busy" whena logger calls out, severalattempts
may be programmed by using the retry (RETRY) parameter.
When an intelligent modem is used with the logger it is important to turn off responses (RE=off)
so that logger messages such as "Command Error" , "Going to Sleep", "Waking Up" and "CR LF"
do not cause the modem to issue a reply, which will cause the logger to reply, which will cause the
modem to reply, etc...
Each rainfall and river event that is logged is also transmitted on the serial port, unless the event
output flag is off (EV=off). This flag should be off when the logger is connected to an intelligent
modem.