UNIDATA
Unidata Manual 6293 - Precision Water Level Instruments Issue 2.1
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4.3.1 HSIO Interfaces.
The 6541B has two HSIO interfaces. The primary interface is accessible via the
screw terminals at the front of the instrument. The secondary HSIO interface is
accessed by the IDC header located low on the rear of the PCB and is intended for
connection to a Micrologger. When fitted with a Micrologger the 6541B becomes a
standalone logging instrument.
The HSIO interface wiring shall be configured as below:
4.4 Connecting More Than One Instrument to a Logger
Each serial channel on a STARLOGGER or PROLOGGER will support up to eight
“daisy-chained” instruments. The first encoder’s DATA IN (blue wire) connects to
the logger’s serial channel input (S0); the second encoder’s DATA IN (blue wire)
connects to the first encoder’s SERIAL LINK (white wire, S1) and so on.
The +5V DC (red), COMMON (green) and SERIAL CLOCK (yellow) signals must
be connected in parallel at the logger or the adjacent encoder’s terminal block if that
is more convenient.
4.5 SDI-12
Interface.
The 6541B Water Level Instrument has a Version 1.3 - compliant SDI-12 sensor
interface. As the 6541B generally has its own battery power source, only two wires
are required for the sdi-12 communications. These are GND and SDI-12 for the data.
Generally sdi-12 sensors are not continuously powered and upon receipt of an sdi12
command they need some time to take their measurements before reporting these
measurements back to the recorder. The 6541B is powered all the time and
measurements are instantaneously available allowing the use of the aR0! commands.
