All sensors are wired to a "datalogger", which is located nearby. The datalogger runs a small program which automatically operates and collects data from each of the sensors. It can store several days of readings in its on-board memory.
A computer, located at the bottom of the mountain, is used to communicate with the datalogger over a serial link. The computer collects and stores weather information, and makes the information available in the form of web pages.
The datalogger contains a small microprocessor which runs a locally written program. It has the capability, under program control, to periodically wake-up, stimulate and control various sensors, convert analog-to-digital measurements, perform calculations and format the collected measurements into a data record.
Manufacturer / Model: Campbell Scientific / CR10X datalogger
Hardware:
Software:
;{CR10X} ; *Table 1 Program 01: 60 Execution Interval (seconds) 1: Do (P86) 1: 41 Set Port 1 High 2: Excitation with Delay (P22) 1: 1 Ex Channel 2: 0000 Delay W/Ex (units = 0.01 sec) 3: 15 Delay After Ex (units = 0.01 sec) 4: 0000 mV Excitation 3: Volt (SE) (P1) 1: 1 Reps 2: 5 2500 mV Slow Range 3: 1 SE Channel 4: 1 Loc [ Temp_F ] 5: 0.18 Mult 6: -40.0 Offset
Power: Twelve (12) Volts DC, provided by multiple diode-isolated sources: In our case, a line-powered AC power supply and some rechargeable batteries for back-up. The datalogger should operate until the power rail drops below 9.6 Volts.
Attempts to rely on photovoltaic cells were unsuccessful due to the limited amount of solar energy available due to clouds and rime. Solar input is limited by the shortened daylight hours of winter, cloud cover, and the cells being obscured by a lingering rime build-up during the relatively brief periods of sunlight which follow storms.
A second challenge of photovoltaics and rechargeable batteries is the delay to recharge depleted batteries back up to an operational voltage. A smart power management scheme would allow immediate operation from sunlight-only, while the batteries are slowly recharging.
Connections:
- Sensors - listed with specific sensor
- Serial data -
Proprietary ribbon cable to RS-232 interface
Manufacturer / Model:
Campbell Scientific Inc., (Logan, Utah) /
SC932(C)
Connections:
Power:
This modem interfaces to an RS-232 serial port. It uses balanced line drivers
and receivers and two twisted-pair wire connections to communicate with an
identical unit at the other end of the line. At the far end, the other modem
converts the signaling back to the RS-232 standard.
Manufacturer / Model: RAD Data
Communications / SRM-5A &
SRM-5A (pdf)
Distributor / Model:
Campbell
Scientific, Inc. (Logan, Utah) /
SRM-5A
Serial data connections:
Power:
Additional Notes:
Manufacturer / Model:
Same as the modem at the datalogger.
Serial data connections:
Power:
Operating system: Windows XP
Software:
Connections:
Power: Via an Uninterruptible Power Supply (UPS)
9-pin to RS-232 DCE Interface
Function:
This unit converts the
datalogger's serial port to a standard RS-232 serial interface.
- Serial data - Proprietary ribbon cable to
datalogger
- Serial data - Direct connection to the modem
- Provided via the datalogger interface cable
Short haul modem
Function:
The short haul modem makes it
possible to operate a serial data link over a much longer distance than would be
possible using a standard RS-232 serial connection.
- To RS-232 interface - direct connection
- To the downhill line:
Terminal 2-pair line to panel 25-pair line (to bottom)
XMT + Yellow Black Red Green .
XMT - Yellow Black Red Green .
RCV + Yellow Black Red Green .
RCV - Yellow Black Red Green .
- Derived from RS-232 interface connection
- A 25-pair telephone grade cable was used to
provide in-the-ground copper wire connections between the datalogger and
computer. This installation included surge suppressors at both ends of the line
to minimize the potential for damage due to lightning.
At the Computer
Short haul modem
Function: Same as the modem at the datalogger.
- To the uphill line -> datalogger end
Terminal 2-pair line to panel 25-pair line (from top)
XMT + Green .
XMT - Red .
RCV + Yellow .
RCV - Black .
- To computer - Directly onto
the computer's 25-pin COM[1,2] RS-232 serial port connector
- Derived from serial data line from computer
Computer
Function:
To collect, re-format, store and make use of
the weather sensor data which is measured.
EDLOG - Campbell Scientific's program for datalogger program
development
PC208W - Campbell Scientific's data acquisition program
for communicating with the datalogger
cron - Locally written program which coordinates program operations.
trimmer - Locally written program which re-formats the
captured datalogger data and organizes its long-term storage.
- Serial COM[1/2] port to datalogger via short haul modem
- Serial COM[2/1] port to snow depth sensor via short haul modem
- Internal modem to telephone line
- Network to lodge's local area network (LAN)