OAP – Weather Sensing – Detailed Design Document

Overview:

Background and scope:

Weather sensing is used to determine current and possible future conditions while observing. There are several forms of information available to the observer to help determine these conditions. This project will meet the requirements necessary to allow safe, remote observing thereby protecting the telescope, instruments and observatory from inclement weather.

Currently, the OA will read weather information via the web and on dials (in the control room). The OA will walk outside the building to get a feeling of current weather conditions available and perhaps, what is on the horizon. The OA might call other observatories and get ideas on current conditions. If the weather is nice, there would seem to not be a problem. If weather is BAD, the determination would be easy to assess. It would seem when the weather is transitioning to bad that we have a concern.

What do we have now? - Basic Description.

  • Weather Tower - Documentation
  • Wind Speed - Hydrotech heated anemometer mounted atop CFHT weather tower
  • American Meteorological Society Research
  • Wind direction - Hydrotech heated wind vane mounted atop CFHT weather tower
  • Vaisala HMP-45A RH/Temperature sensor mounted in aspirated radiation shield approximately 10 feet up from bottom of CFHT weather tower
  • Rain Gauge (Documentation)
  • CFHT Data logger
  • Various available temperatures throughout observatory environment (Including Temperature and Humidity at top of dome (outside)
  • RH in various places
  • Barometric Pressure – Measured 600-1100mBar in Control Room
  • Other observatories
  • Web pages
  • Verbal access through the phone
  • Tools to help monitor the sky remotely in order to replace summit visual checks. (all sky camera?)
  • Cloud sensor
  • Skyprobe
  • OA
  • Ability to detect icing conditions
  • Use flashlight to shine up in the sky to determine sky conditions (moisture, particulates, etc.).

Requirements:

From the Weather Sensing Conceptual Design Review, the following requirements have been defined:

  • Remotely monitor the weather.
  • "Particulate" sensor to detect falling snow (No Dust sensor required per CDR).
  • Tools to help monitor the sky remotely in order to replace summit visual checks.
  • Covered under the Audio/Video project - East facing IR camera.
  • Ability to detect icing conditions.
  • Dew point calculations using Temperature and RH measurements in various places.
  • Surface temperature sensors mounted on catwalk, external observatory wall and top of dome.
  • Delivery of data to user to be on the order of 1 second latency after sampling -This will be on the Status Server side of things.
  • Updates will be on the order of 10 seconds. -This will be in the Status Server side of things.

As is documentation:

Block Diagram of existing system:

The Current Weather sensors comprise of two different distinct systems. The first system comprises the old sensors made by Qualimetrics. The secondsystem includes the sensors installed on the weather tower.

  • Qualimetrics Sensors on top of Dome and in control room (Documentation reside in a binder):
  • Temperature and Relative Humidity (RH) sensor mounted in a radiation shield atop the dome.
  • The wires go through a junction box down a conduit into a junction box inside of the dome.
  • The wires feed into a Multiplexer and then an FM transmitter.
  • An antenna resides on the mezzanine of the 5th floor. The signals are received and routed down into the control room's rack at knee level of the OA console.
  • The signal enters into a FM receiver and then gets demultiplexed and fed into their respective driver boards.
  • The driver boards drive gauges and/or the data logger.
  • The Barometric sensor is mounted in the control room.
  • Sensor receives power from the control room's rack at knee level of the OA console.
  • Sensor signal is fed back into the control room rack's driver boards.
  • The driver board drives gauge and/or the data logger.
  • Weather Tower Sensors (Documentation) include:
  • Wind Speed - DC generator voltage scaled 0-200 knots wind speed fed into PLC analog input module at base of tower.
  • Wind Direction - 0-5 volt DC signal scaled 0-360 degrees fed into PLC analog input module at base of tower.
  • Temperature and RH - 0-1 volt signals representing -40 to 60 C and 0-100% RH fed into PLC analog input module at base of tower.
  • Rain Gauge (Documentation) - Momentary pulse representing 0.01" of rain. Signal triggers 24 volt discrete input bit of PLC module mounted at base of tower.

Selected Design Alternative:

Block Diagram of New System:

From the above block diagram, the only unknowns (new) pieces of hardware are the snow/rain sensors and barometric pressure sensor. All other sensors and devices are well understood and have proved to be cost effective, very reliable, and easy to maintain solutions.

PDR Review Notes:

From the PDR, the following items were selected:

  • Rain Snow sensor:
  • Automated Systems Engineering (ASE) DS-4
  • Installation Manual
  • Information
  • Barometric Sensor:
  • Vaisala PTB110
  • Data Sheet

From the PDR, the following was determined:

  • The Weather PLC in the control room will no longer be wired directly to the Data Logger. The data will be directly read from the PLC processor.
  • The video camera plus flashlight tests are progressing. David and Rachael have done tests on nights with snow/blowing ice as well dust.
  • Maximum power consumed by the DS-4 Rain/Snow sensor is 15W. This means the internal heater will not put out anything close to that.

Important NOTE:

Although not a “requirement” from the OAP project, the new system will do away with the RF Transmitter/Receiver placed at the 5th floor mezzanine area. The sensor data will be collected by the Dome Shutter PLC processor. The data will be available via the Ethernet channel via common PLC reads by the OAP Status server.

Important NOTE II:

Per the Atmospheric Seeing Monitor Design Review, Rain/Snow sensor will not be mounted on the weather tower.

After some investigating at the summit (5 April 2009), I propose a small change to the original design of how the dome top sensor data is collected. The block diagram below depicts this change:

.PNG Verson

The original design shows the sensor signals coming down from the top of the dome and routing over to the Dome Shutter PLC. The distance from the junction box (weather sensors) to the Dome Shutter PLC box is approximately 102 feet. This means that each and every one of the sensor signals have to first come down from the top of the dome and then travel the additional 102’ to the dome shutter PLC area.

I propose mounting the Dome Weather PLC crate where the current Qualimetrics crate is located. This is where the weather sensor currently arrives from the top of the dome. There, I will have a SLC/503 processor mounted to collect the data. A RS232 cable will link the SLC 5/03 processor to the Dome Shutter PLC. I chose this instead of a 5/05 Ethernet processor because of costs and the fact that we have available a number of these processors that are not being used.

This will have the following benefits:

  • Shorter Cable runs
  • Instead of 19 wires (6 cables) spanning the 102’ distance, only 1 cable with 3 wires will be required.
  • Less cost
  • Less long cabling to be installed - $$
  • No need for Rack Extension Cable - $160.00
  • 1 less junction box required - $580.00
  • SLC 5/03 processor already in hand, with spares

Picture Showing Weather Sensor Junction Box.
/ Picture of Dome Shutter PLC Box.
Original design was to place an additional junction box in the lower space beside the Shutter PLC Box.

Closer look of Weather Junction Box.
Notice antenna above, this will be removed.
/ Inside look of Junction Box.
Qualimetrics crate will be removed and a PLC rack will be put in its place.

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Detailed System Design:

Drawings – Schematic Diagrams:

Tower Schematic Diagram – Removal of Weather Tower Rain/Snow Sensor reflected in this schematic.

.PNG Version

Autocad Version

Dome Shutter PLC – Weather Sensors – Drawing does not show 5/03 processor. All cards will shift to right by one and the interconnect cable on right will go away.

.PNG version

Autocad version

Telescope (CS5) Sensors Schematic Diagram:

Page 1 – PLC Hook Ups

.PNG Version

Page 2 – Sensors and Mechanics:

.PNG Version

Autocad Version – Pages 1 and 2

Control Room Weather PLC:

.PNG Version

Autocad Version

Page 1 of 24

Cable Length Calculations:

Overall 4th Floor View:

.PNG Version

  • Diameter of Observatory Building is approximately 92.8 ft.
  • Circumference = 2π(92.8) = 583 ft or about 1.62 ft/degree
  • Estimation of distance from skin of dome to catwalk and then up to top of catwalk is 10 ft.
  • Note approximate locations of CFHT Webcams.
  • Detail of cable route from Weather PLC in control room to computer room and then to outside.

.PNG Version

  • Length of cable from PLC mounting location to get outside of dome ~ 59 ft
  • 10 ft to go up and down from PLC to cable tray
  • Approximately 30 degrees of dome at 1.62 ft/degrees = 49 ft
  • Calculations to Cameras (Rain/Snow Sensors)
  • SW Camera cable length (Mounting location for SW Rain/Snow Sensor) ~ 119 ft
  • 59ft from PLC to dome skin
  • 50 ft along outside skin back towards camera
  • 10 ft to cross catwalk and up railing
  • NW Camera cable length (Mounting location for NW Rain/Snow Sensor) ~ 174 ft
  • 59ft from PLC to dome skin
  • 65 degrees of dome * 1.62 ft/degrees = 105 ft
  • E Camera cable length (Mounting location for E Rain/Snow Sensor) ~ 272 ft
  • 174 ft to NW camera
  • 60 degrees of dome (beyond NW camera) * 1.62 ft/degrees = 105 ft
  • Calculations to temperature sensors mounted on catwalk railing and dome skin.
  • West Temp Sensor ~ 65 ft
  • 59ft from PLC to dome skin
  • 3 degrees of dome * 1.62 ft/degrees ~ 6
  • West Catwalk Temp Sensor ~ 75 ft
  • Add 10 ft to West Temp Sensor
  • South Temp Sensor ~211 ft
  • 65 ft to West Temp Sensor
  • 90 degrees of dome * 1.62 ft/degrees ~ 146
  • South Catwalk Temp Sensor ~ 221 ft
  • Add 10 ft to South Temp Sensor
  • North Temp Sensor ~211 ft
  • 65 ft to West Temp Sensor
  • 90 degrees of dome * 1.62 ft/degrees ~ 146
  • North Catwalk Temp Sensor ~ 221 ft
  • Add 10 ft to North Temp Sensor
  • East Temp Sensor ~357 ft
  • 65 ft to West Temp Sensor
  • 180 degrees of dome * 1.62 ft/degrees ~ 292
  • East Catwalk Temp Sensor ~ 367 ft
  • Add 10 ft to East Temp Sensor
  • All other cable runs are not significant in length and we should be able to use existing stock.
  • Cable Length Total

Description / Length (ft)
SW Camera Location / 119
NW Camera Location / 174
E Camera Location / 272
W Observatory Temperature Sensor / 65
W Catwalk Temperature Sensor / 75
S Observatory Temperature Sensor / 211
S Catwalk Temperature Sensor / 221
N Observatory Temperature Sensor / 211
N Catwalk Temperature Sensor / 221
E Observatory Temperature Sensor / 357
E Catwalk Temperature Sensor / 367
Total: / 2293

Data Sheets:

  • Hydrotech Wind Vane and Anemometer
  • Vaisala HMP-45A RH/Temp Sensor
  • Rain Snow Sensor
  • Installation Manual
  • Information
  • Vaisala PTB110 Barometric Sensor Data Sheet

Test or Prototype Results:

  • Have verified operation of the ASE DS-4 Rain/Snow Sensor. Will be taking to summit to do installation on the dome catwalk. This will allow us to start collecting data ASAP.

Control System Design:

  • PLC based
  • Here is an example of how the PLC will read data, calculate a result and put in an available register for the Status Server to read.
  • The little “snippet” below shows calculation of Wind Speed and Relative Humidity.
  • Wind Speed – Take the number in N7:0 multiply by 10 and divide by 32,767 and multiply all of that by 20 and put the result in F20:0 – The Wind Speed at the time was 15.36 Knots.
  • RH – Take the number in N7:1, multiply by 10, divide by 32,767 and multiply by 100 and offset the value by 2.3 and finally put the result in F20:1 – The RH at the time was 40.6%.
  • Processors will collect data from sensors and put into data registers to be read from the Status Server
  • Please see below in Interface Definition
  • Control Modes
  • None – Systems will collect data and have available for Status Server to read
  • GUI Mock Up
  • TBD – Will be based on discussions with OA/SO and others. Currently we have various strip charts via OAP GUI and TCS

Detailed Interface Definition:

  • Software
  • Tower PLC
  • IP Address – 128.171.83.XXX
  • The tower PLC will collect the raw sensor data and have data available in registers for the Control Room Weather PLC to access and scale for the Status Server to read
  • The Control Room PLC will also display the data via the Control Room Gauges
  • Dome Shutter PLC – Weather Sensors on top of dome
  • IP Address – 128.171.83.152
  • Dome shutter PLC will use MSG command (same as Weather Tower PLC data exchange) to acquire data from the Dome Weather PLC.
  • F50:0 – Top of Dome Relative Humidity
  • F50:1 – Top of Dome Temperature
  • F50:2 – Top of Dome Skin Temperature 1
  • F50:3 – Top of Dome Skin Temperature 2
  • F50:4 – Top of Dome Skin Temperature 3
  • F50:5 – Top of Dome Skin Temperature 4
  • B51:0.XX – Rain/Snow Sensor Status

15 / 14 / 13 / 12 / 11 / 10 / 9 / 8 / 7 / 6 / 5 / 4 / 3 / 2 / 1 / 0
X / X / X / X / X / X / X / X / X / X / X / X / X / X / Dome Top Sensing
Snow / Dome Top Sensing
Rain
  • Control Station 5 (CS5) – Primary Mirror Environment Relative Humidity and Temperature.
  • IP Address – 128.171.83.108
  • F50:0 – RH above mirror covers
  • F 50:1– Temperature above mirror covers
  • F50:2– RH below mirror covers
  • F50:3– Temperature below mirror covers
  • Control Room Weather PLC
  • IP Address – 128.171.83.10
  • Will retrieve necessary data from the Weather Tower PLC and Dome Shutter PLC (Dome Top sensors) so it can drive the gauge displays in the control room.
  • Weather Tower
  • F20:0 – Wind Speed (Knots)
  • F20:1 - Relative Humidity (Weather Tower)
  • F20:2 – Temperature (Weather Tower)
  • F20:3 – Wind Direction
  • Control Room
  • F20:4 – Barometric Pressure
  • Top Of Dome
  • F20:5 – Relative Humidity (Top of Dome)
  • F20:6 – Temperature (Top of Dome)
  • Skin Temperatures
  • F21:0 – Catwalk Temperature North
  • F21:1 – Catwalk Temperature South
  • F21:2 – Catwalk Temperature West
  • F21:3 – Catwalk Temperature East
  • F21:4 – Observatory Skin Temperature North
  • F21:5 – Observatory Skin Temperature South
  • F21:6 – Observatory Skin Temperature West
  • F21:7 – Observatory Skin Temperature East
  • Rain Snow Sensors
  • B22:0.XX – Rain/Snow Sensor Status

15 / 14 / 13 / 12 / 11 / 10 / 9 / 8 / 7 / 6 / 5 / 4 / 3 / 2 / 1 / 0
X / X / X / X / X / X / X / X / X / X / SW -
Sensing
Snow / SW -
Sensing
Rain / NW -
Sensing
Snow / NW -
Sensing
Rain / E-
Sensing
Snow / E - Sensing
Rain
  • Tower Rain Gauge
  • F30:0 - Today’s Accumulated Rain Value (Inches)
  • F30:0 – Last Sunday’s Accumulated Rain Value (Inches)
  • F30:1 – Last Monday’s Accumulated Rain Value (Inches)
  • F30:2 – Last Tuesday’s Accumulated Rain Value (Inches)
  • F30:3 – Last Wednesday’s Accumulated Rain Value (Inches)
  • F30:4 – Last Thursday’s Accumulated Rain Value (Inches)
  • F30:5 – Last Friday’s Accumulated Rain Value (Inches)
  • F30:6 – Last Saturday’s Accumulated Rain Value (Inches)

Implementation and Test Plan:

The Implementation process of this project will progress in stages. This will allow installation and then integration with the fewest impacts on observing. Gemini and others will be made aware of any down time to the available data. An attempt will be made to never allow any lapse of weather data during observing hours.

Some of these items can occur in parallel dependant on available man power.

Migration to the new systems will be as new sensors are installed and brought on line. We have a very good history with all of the sensors except the Barometric Sensor.

I am making an attempt here to give a brief description as to what each job entails as well as how long it might take. The intention here is to see if I thought of everything as well as recruitment for help. I will not be heartbroken if anyone relieves me of any of the tasks. I have put myself down for almost all of the work because I cannot speak for anyone else out there as far as commitments.

  • Start – Immediately as Detailed Design accepted.
  • Weather Tower – 1 day (GM/??)
  • Change PLC processor from 5/03 (RS232 model) to 5/05 (Ethernet) model.
  • NO PLC code change yet – this will create the least amount of down time.
  • Swap out RS232/Fiber converters for Ethernet converters.
  • Make PLC code change to control room PLC to read weather tower data via the Ethernet port vs. RS232 port.
  • Control Room PLC
  • Install SW Rain/Snow sensor (DS-4) on to catwalk. (LR, GM) – 1 day.
  • This item can commence ASAP. We have the unit in hand and will allow us to get a baseline and feel for the unit as it operates in the CFHT environment.
  • Route cables from SW DS-4 to PLC in control room.
  • Do upgrade to PLC (GM) - 1 day
  • PLC chassis (from 4 slot chassis to 10 slot chassis)
  • Install Vaisala Barometric Sensor and wire to PLC I:5.0 (Input module).
  • Install sensor, do wiring but do not make cut to BP display yet. Qualimetrics equipment will continue to display BP so we can make an assessment over a period of time.
  • Install 8 Input RTD Module – Read Surface Temperature (Catwalk and Observatory skin)
  • Install 24 volt, 16 bit input module – Read Rain/Snow Sensors
  • PLC code changes to accommodate the above changes.
  • Wire SW DS-4 to input module.
  • As time permits – 3 days (GM/??/Daycrew)
  • Install DS-4 in NW and E locations and route cables to control room PLC
  • When cables are routed, will be hooked up to PLC.
  • Install Catwalk and Observatory skin temperature sensors and route cables to control room PLC.
  • When cables are routed, will be hooked up to PLC.
  • CS5 PLC
  • Waimea – (GM/??) 1 day.
  • Fabricate mounts for HMP-45A RH/Temp sensors (2 ea) – (1/2 day prep in Waimea).
  • Summit – (GM/??) 1 day.
  • Mount sensors in their locations
  • Route cables to CS5 PLC.
  • PLC upgrade:
  • Wire sensors to PLC analog input module
  • I:7.4 – RH Above Mirror Covers
  • I:7.5 – Temp Above Mirror Covers
  • I:7.6 – RH Below Mirror Covers
  • I:7.7 – Temp Below Mirror Covers
  • PLC code change to read sensors and have data available for Status Server
  • Dome Shutter PLC and Dome Top Sensors.
  • Waimea
  • Build up new PLC rack to house – 3 days (GM/Bauman??)
  • SLC 5/03 processor (recycled from many that are in hand)
  • Program PLC to collect all the data
  • New PS2 Power Supply
  • 7 Slot Rack
  • Analog 8 input module (1746-NI8)
  • 8 input temperature (1756-NR8)
  • Summit
  • Qualimetrics Rack – 2 days (GM/Bauman)
  • Shut down power and remove hardware from junction box
  • Install new PLC rack
  • Fabricate and string RS232 cable from rack to Dome Shutter PLC RS232 port
  • Hook up sensor wires to PLC
  • Dome top sensors - This item will probably experience a few days of down time without available data.
  • Radiation Shield with HMP-45A sensor and DS-4 sensor – 1 day (GM/Daycrew)
  • Remove radiation shield from top of dome and bring to machine shop
  • Modify radiation shield to accommodate new sensor
  • Install new sensor into shield
  • Fabricate mount to install DS-4 to top of dome
  • Following items can be completed at the same time – 1 day (GM/Daycrew)
  • Install DS-4 to top of dome.
  • Install DS-4 on top of dome
  • Wire to dome top junction box
  • Install skin temperature sensors.
  • Install skin temperature sensors
  • Wire to dome top junction box
  • Install radiation shield and wire to junction box at top of dome – 1 day (GM/Daycrew)
  • Dome Shutter PLC – 1 day (GM/Look/Bauman?)
  • Connect RS232 Cable to Dome Shutter PLC processor
  • Install new Dome Shutter PLC code to read Dome Top Sensor data and put into registers (See Software Interface section)
  • PLC code change to offset and calibrate sensor data
  • PLC code change in Control Room to access Dome Top HMP-45A data

Draft Spares List: