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RS-485 Terminals
A (-):
B (+):
GND:
+VDC:
RS-485 is rated to 4,000 feet (1,200 m) at 90 kbps. The RS-485 port on the PVMET-330
is surge protected but not isolated.
Connecting the Power Supply
The weather station can either be powered from its own battery and solar panel or from
an external power source (depending on model). For systems running with external
power, a cable connection must be made between the RS-485 interface board and the
motherboard. A cable is provided and should already be connected to J2 on the RS-485
board. To switch to external power disconnect the solar panel cable and connect the
power cable in its place. The system will then be powered via the solar panel input
connector. These connections will already be made if the system is ordered without the
solar power option.
The power supply input is nominally rated for 24VDC but can accept a voltage in the
range of 10 to 30VDC. The inputs are reverse polarity, surge, overvoltage and over
current protected. The power supply is not isolated.
When replacing the cover, make sure that all installed cables are pinched by the black
foam on the bottom of the enclosure. This will enable a weather tight seal.
MODBUS RTU
These weather stations are equipped with a RS-485 communications port that supports a
subset of Modbus RTU commands. Two board rates are supported 9600 and 19,200.
Only 4X Holding registers are supported. The register map that follows describes each
register. These stations are read only.
C
OMMUNICATIONS
Baud: Switch 5 selects the baud rate. ON=19200, OFF=9600 (default).
Data bits: 8
Parity: None
Stop Bits: 1
Maximum Poll Rate: 5 Hz (Extended periods of rapid polling will drain the battery)
S
CALING
Parameters are reported as integers. In order to maintain resolution some values are
scaled up. The scale factor shown indicate how the value should be scaled. "-1" indicates
that the value should be multiplied by 10^-1 or simply divided by 10. Rainfall is an
exception; this parameter reports the number of tips of the tipping bucket rain gauge.
Typically, the gauge is calibrated to 0.254mm (0.01") per tip. This counter resets on a
reboot and will roll over at 65536 counts.
Negative RS-485
Positive RS-485
Signal/Power Ground
External 10-30VDC Supply
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