1

DIGITAL CURRENT WEATHER INDICATING INSTRUMENT

SYSTEM MANUAL

PREPARED BY ELECTRONICS LAB

O/o DDGM(SI), PUNE

INDIA METEOROLOGICAL DEPARTMENT

2

CONTENTS 1. BLOCK DIAGRAM 2. DCWIS PARTS

2.1 DATA DIGITIZER 2.2 CONNECTION DETAILS(METLOG-3) 2.3 CONNECTION DETAILS(METLOG-4) 2.4 TTRH SENSOR WIRE DETAILS(MICROSTEP AND

KOMOLINE) 2.5 PRESSURE SENSOR WIRE DETAILS(VAISALA PTB330) 2.6 WIND DIRECTION SENSOR 2.7 ULTRASONIC WIND SENSOR(GILL MAKE) 2.8 RF COMMUNICATION AT TX/RX END(METLOG-3 AND

METLOG-4) 3. DATA LOGGER 3.1 COMMUNICATION TO COMPUTER AT RX END 3.2 DISPLAY CONNECTIONS 4. CONFIGURATION AT DIGITIZER(METLOG03)

5. CONFIGURATION AT DIGITIZER(METLOG-4)

5. FREQUENTLY ASKED QUESTIONs /PROBLEMS FACED for DCWIS

6. CONNECTIONS OF 10k SERVOPOT AND NORTH SETTING WIND VANE

7. ROUTINE OPERATING PROCEDURES

For suggestions and feedback please write to si.elab@imd.gov.in. Your

feedback and suggestions will surely help in making a more comprehensive

manual .

3

DIGITAL CURRENT WEATHER INSTRUMENT SYSTEM: - DCWIS

1.Block Diagram for CWIS

TX END/RUNWAY SITE

RS232 Ethernet

COM3 PoE

RX END/MBR SITE/ATC TOWER

Ethernet RS232 RS422(Pin8,9)

PoE COM3

RS232 COM4 RS422

DIGITIZER

Temp/pressure/

windspeed/dire

ction sensors

SERIAL TO

ETHERNET CONVERTOR

Wi-Fi

Modem/Cable

Modem

Wi-Fi

Modem/Cable

Modem

SERIAL TO

ETHERNET CONVERTOR

Pin 1,2

DATA LOGGER

DISPLAY AT

MBR

DISPLAY AT

ATC

COMPUTER

4

2.DIGITAL CURRENT WEATHER INSTRUMENT SYSTEM: - DCWIS This system contains following main parts: a. Data Digitiser b. Data Logger c. Slave Displays Indicating Weather Parameters with Pressure d. Mini Slave Display Indicating Wind Parameters e. Wireless Modems f. Wired Modems g. PC Software

2.1 DATA DIGITIZER: Data Digitizer is located near Runway touchdown zone. Data Digitizer performs following functions: · Reads various weather sensors connected to it. · Converts the sensor values into digital format · Transmits the data over Wireless Modem to Data Logger · Transmits the data over cable modem to data logger · Stores the data as a redundancy

Parameter Sensor Type Excitation

Voltage Output Make & Model

Temperature – Humidity Sensor

Temperature 12 V DC 0 – 1 VDC

-40°C to +60°C Rotronic – HC2 / Vaisala

Humidity 12 V DC 0 – 1 VDC

0 – 100 %

Wind Direction Wind Speed Sensor:

Option 1 - Ultrasonic

Wind Direction Ultrasonic 12 VDC

RS232 9600-8–N-1

Gill Sensor Wind Speed

Option 2 : IMD Make

Wind Speed Optical

Anemometer 12 VDC

RS232 4800–8–N–1

IMD

Wind Direction

10 K Potentiometric

-- 0 – 10 K IMD

Hall Effect 12 VDC 0 – 20 mAmp IMD

Pressure Sensor

Barometric Pressure

Digital 12 VDC Adjustable RM Young

Digital 12 VDC Adjustable ThiesClima

Digital 12 VDC Adjustable Microcomm

5

2.2 CONNECTIONS OF ALL SENSORS TO DIGITIZER(METLOG-3)

Analog Connector

PIN No. Description

PIN No. Description

1

TXD1 (Blue wire from Optical Anemometer)for calibration purpose only.

17 Potentiometric Wind Vane + (One of the two wires from wind vane )

2 NC 18 Potentiometric Wind Vane - / (Other wire of wind vane)

3 RXD1 (WS Input) (Yellow Wire from Anemometer) SIGNAL CABLE

19 +12VDC#

4 NC 20 NC

5 GND for optical Anemometer (Black Wire from Anemometer) GROUND

21 Temperature Input # (0 – 1000mV)

6 NC 22 Analog Ground#

7 NC 23 Analog Ground

8 Ground 24 Humidity# (0 – 1000mV)

9 NC 25 NC

10 NC 26 +12VDC(POWER TO PRESSURE SENSORE)$

11 Ground (Short with PIN No. 32 for GROUND)

27 NC

12 NC 28 NC

13 NC 29 NC

14 Ground 30 NC

15 +12V DC (Red Wire from Anemometer)POWER SUPPLY

31 Analog Ground(GROUND FOR PRESSURE SENSOR)$

16 NC 32 Analog Ground (Short with PIN No. 11 for GROUND)

# : # marked pins are for TTRH sensor, different make sensor have different

colour code. Colour code of these sensors is included in SECTION 2.3

$: $ marked pins are for pressure sensor power, different make sensor have

different colour code. Colour code of these sensors is include in SECTION 2.4

PIN 11 and PIN 31 are shorted for giving common ground.

6

2.3 CONNECTIONS OF ALL SENSORS TO DIGITIZER(METLOG-4)

PIN NO. Description PIN NO. Description

1* 12 V DC(ATRH Power)

11 NC

2 Wind Direction/Hall effect(+)

12 NC

3 Wind Direction/Hall effect(-)

13 NC

4# Ground 14 NC

5 Temperature 15* 12 V DC(Pressure Sensor Power)

6 Humidity 16 NC

7 NC 17* 12 V DC(Anemometer Power)

8 NC 18 NC

9 NC 19 WS(Input)

10 NC 20# Ground

*Pins 1,15,17 are 12 VDC output for sensors

#Pins4 and 20 are ground for sensors

7

2.4 TTRH SENSOR WIRE DETAILS

1. Microstep Make RHT 175

1. Komoline make KAS-011 Air Temperature and Relative Humidity

Sensor

Red Wire: +12 V DC

Black wire: Ground

White wire: Temperature(+)

Blue Wire: Temperature(-)

Yellow/Orange: Humidity(+)

Green wire: Humidity(-)

RHT175 – V1.1 IMD Datalogger

PWR (+12 V)

GND (-12 V)

Shield GND

Analog Signal GND

Analog Humidity (0-1 V)

Analog Temp. (0-1 V)

Pink

Blue

Violet

Thick Black

Brown

White

8

2.5 PRESSURE SENSOR WIRE DETAILS

1. VAISALA MAKE PRESSURE SENSOR(PTB 330)

Open the Vaisala make PTB 330 sensor with help of Allen key. Inside the sensor

green connection terminal is available as shown in above figure.

Tx, Gnd and Rx are for serial data (RS232) output from the sensor(2). Power

supply is connected at +(10-36 V DC) and –(GND) markings.

Short the GND terminal in RS 232 with –(GND) in power option so that ground

to serial output can be provided.

For connecting the pressure sensor to Data Logger:

TxD ------Pin2 of DB9 Connector

RxD------Pin3 of DB9 Connector

GND-----Pin5 of DB9 Connector

This DB9 connector is connected at the COM4 port of Digitizer.

Setting in Digitizer/Data Logger for pressure sensor:

i) Press and hold Enter key or PGM key in data logger.

ii) Press password as: “INC SEL INC SEL” for METLOG4 and “INC SHIFT INC

SHIFT” for METLOG3.

Short the RS232 ground

with power ground

internally

9

iii) With INC button go to PR Sensor Type and select the sensor being

used.

iv) Similarly go to PR Station Height Menu and enter height of station

from mean sea level.

v) Then go to PR sensor height menu and enter the height of pressure

sensor from ground.

2.6 WIND DIRECTION SENSOR :

Two types of wind direction sensor are used at present:

1. Potentiometric wind vane:

This sensor is having two wires having some resistance as per position of

potentiometer according to wind direction. These two wires are to be

connected at pins described in table having PIN details irrespective of

colour.

2. Hall Effect Wind sensor:

This sensor is having 4 wires , 2 for power and 2 as output. Positive of

power is connected with 12 V DC and negative with ground. Signal wires

are connected at positive and negative pins as mentioned in PIN

description table.

Two configure the data logger/digitizer with taking input one of wind vane

following steps are to be followed:

i) Press and hold PGM or Enter key on data logger.

ii) Go to Config setting with help of INC button.

iii) Enter with password: “INC SEL INC SEL” for METLOG4 and “INC SHIFT INC

SHIFT” for METLOG3.

iv) Move down with INC button and go to WD Sensor type.

v) Press enter and select POT for potentiometric wind vane or Hall effect for

Hall effect-based wind vane

10

2.7 ULTRASONIC WIND SENSOR:

Digitizer is having feature to interface Gill make ultrasonic wind sensor.

To interface Gill Make Ultrasonic wind sensor:

1. Connector positive of power cable of sensor at 12 VDC terminal and

Negative at GND terminal.

2. TXD wire of from sensor is connected at WS input pin at Digitizer.

3. Press and hold PGM or enter key on digitizer and go to config setting

with INC button.

4. Enter with password: “INC SEL INC SEL” for METLOG4 and “INC SHIFT INC

SHIFT” for METLOG3 and go to WS sensor type.

5. Select the sensor type “ULT”. Then go to ULT baud rate and set it to

9600 or at known baud rate of sensor.

2.8 RF COMMUNICATION AT TX/RX END

METLOG-3

These PINS are of RS232 connector,

corresponding wires are to be connected at

Serial to Ethernet convertor as listed in

table i.e PIN2 wire of RS232 cable is

connected at RX Pin of serial to Ethernet

convertor. Similarly for other two pins PIN and wire shall be

identified with the help of multimeter. If there is direct provision of

connection 9 Pin RS232 connector(see image of convertor) then

complete cable is to be used to connect at the convertor.

COM 3Connector : For Wireless Modem (RF) Communication Pin 2 RXD

Pin 3 TXD

Pin 5 GND

11

Ethernet output from convertor shall be connected to Wi-Fi modem

via Po

FIELD SITE

FROM COM 3 Network AP/BRDIGE

OF DIGITIZER

ATC SITE

AP/BRDIGE Network TO COM3 of DATA LOGGER

METLOG-4 In METLOG-4 direct ethernet output is available . Hence direct ethernet cable is to be connected to the modem via PoE

FIELD SITE

FROM ETHERENT OF DIGITIZER Network AP/BRDIGE

ATC SITE

AP/BRDIGE Network PC/LCD Display

ETHERNET

cable from

convertor

PoE

Wi-Fi Modem

Wi-Fi

MODEM

PoE

CONVERTOR

PoE

Wi-Fi Modem

Wi-Fi

MODEM

PoE

12

3.DATA LOGGER:

Data Logger is located at ATC / MBR. Data logger performs following functions: · Stores the data in internal Memory · Output Data over RS232 port for PC Software · Through PC Software user can monitor all the parameters in run time · Transmits the data over RS422 to Slave Display. · Stored data can be downloaded on a PC using Windows based PC software provided with the System.

3.1 COMMUNICATION TO COMPUTER AT RX END (FROM DATA

LOGGER) RS 232

3.2 DISPLAY CONNECTION

Slave display is connected to data logger via RS422. It is connected at

Pin1 and Pin 2 of connector.

Terminal No.

Description

1 TX422+(For Slave Display)(wire from pin 8)

2 TX422- (For Slave Display)(wire from pin 9)

These pin are connected at pin 8 and 9 of RS422 connector. Another

slave display is connected via RS422 cable to the display connected

to logger.

COM 4 Connector: For PC Communication Pin 2 RXD

Pin 3 TXD

Pin 5 GND

13

4.CONFIGURATION AT DIGITIZER(METLOG-3)

1. Press and hold PGM button , following screen will appear

2. Go to CONFIG MODE with the help of INC button and press

enter, it will ask for password

Password :press keys> INC SHIFT INC SHIFT

In CONFIG MODE following options are available

i) WS UNIT: Select the unit of wind speed as required, in

knots for aviation purposes.

ii) WS I/P UNIT: Select unit of wind speed as required.

iii) ULT BAUD: Baud rate for ultrasonic wind sensor

iv) WD INPUT: Select POT or HALL TYPE OF WIND VANE

v) PR MIN: to set Minimum pressure value

vi) PR STAT HT: height of station Above Mean Sea Level

vii) PR SENS HT: Height of pressure sensor above ground.

All value inputs and setting are done with help of INC

SHIFT and ENTER keys.

3. Now after doing CONFIG MODE configuration, press ESC and

return to main screen. Again repeat step 1.

14

4. Now , Go to SYSTEM CONFIG with the help of INC button and

press enter, it will ask for password

Password :press keys>PGM INC SHIFT PGM

In SYSTEM CONFIG following options are available

i) RUNWY NO.: set the runway at which instrument is

installed.

ii) SET CLOCK: set the time

iii) RF BAUD: set the baud the rate for RF communication,

generally 9600

iv) CABLE BAUD: Set the baud rate for CABLE communication,

generally 9600

5.CONFIGURATION AT DIGITIZER(METLOG-4)

Following are general use setting required to configure the data logger at field

site for interfacing the sensors:

1. Press and hold the Enter key, menu will appear on display screen.

2. For Configuration setting, go to CONFIG mode menu with help of INC

key. Password: INC SEL INC SEL

3. Following settings are available under CONFIG mode.

i. WS unit: To select the unit of wind speed like m/sec, knots,

kmph.

ii. WS Sensor type: To select the type of wind speed sensor used

i.e. SER for IMD make optical wind speed sensor and ULT for Gill

make ultrasonic wind speed sensor.

iii. ULT baud rate: To set the Baud rate of ultrasonic wind speed

sensor.

iv. WD Sensor Type: To select the type of sensor used for wind

direction i.e. POT for potentiometric and HALL for hall effect

wind vane.

v. PR STN HT: To set the height of from mean sea level. This is used

for calculating QNH from QFE and observed pressure.

15

vi. PR SENSOR HT: To set the height of pressure sensor from

ground. It is used for calculating QFE from observed pressure.

vii. PR Baud Rate: To set the baud rate as of serial data coming from

pressure sensor. Like 9600 for Vaisala PTB 330 sensor.

viii. PR sensor type: To set the make of pressure sensor like Vaisala,

Setra, Theis or MCOM.

4. For system Configuration, go to System Mode:

Enter the system setting with password INC SEL INC SEL. Following menu

are available:

i. Set Date: To set the Date with Help of INC and Enter Key.

ii. Set Time: To set the Time with help of INC and Enter Key.

iii. RW Number: To enter the Runway number at which system is

installed.

iv. Station ID: station ID for transmission of DATA over GPRS/FTP.

v. Station Name: Name of station where system is installed.

vi. Erase Data: To clear the memory of data logger.

5. For Data backup Via USB:

Enter into USB Mode with password INC SEL INC SEL.

Then select data to be sent to USB in graphical or numerical mode.

6. Calibration Mode:

Password: INC SEL INC SEL

Under calibration mode following Options are available:

1. WS offset: For setting any off in wind speed.

2. WS Multfact: For changing the Slope for calculating wind

speed

3. WD Offset: For setting any off in wind Direction

4. WD Multfact: For changing the Slope for calculating wind

Direction

5. WD Cal: It used for setting the proper gain in the Logger for

wind direction sensor. It basically calibrates the data logger

at 180 direction when proper input is connected.

16

6. TT Offset: For setting any off in Temperature

7. TT Multfact: For changing the Slope for calculating

Temperature

8. DD offset: For setting any off in Dew Point

9. DP Multfact: For changing the Slope for calculating Dew

Point

10. HH offset: For setting any off in Humidity>

11. HH Multfact: For changing the Slope for calculating

Humidity

17

6.FREQUENTLY ASKED QUESTIONs /PROBLEMS FACED for DCWIS

WIND SPEED AND DIRECTION

1. What should be done when Wind Direction at data logger site/ATC site

or in Digitizer at field site is showing”----”?

This may be due to one of the following reasons:

i) POT connection at junction at field site may be loose or wire from

junction box digitizer may be loose. All the wires should be

checked and tightened. If problem persists then follow step (ii).

ii) Check resistance between two wires coming from the wind vane, it

should be varying between 0 to 10Kilo ohm according to wind

direction. It is maximum in case of northerly wind. If resistance is

having some problem then servo pot of the wind vane need to be

changed.

iii) If both (i) and (ii) are ok then problem is with the digitizer.

2. What if wind direction shown by instrument is different from actual

wind direction?

In this case go to filed site and follow following steps

i) Hold the wind vane wind towards north and observe the reading,

then repeat it for east and south. If the difference is almost

constant then it means Servo Pot inside wind vane is displaced.

In this case hold the wind vane fin towards north and rotate the

pot till shows “000” in digitizer and tighten all the screws.

ii) If the difference observed is not constant or nearly equal then POT

is not working and needs to be replaced.

3. What should be done if wind speed is showing “---”?

Go to field site and follow the following steps

i) Check the connections at site in junction box as well as at digitizer.

ii) If connections are OK then check the voltage between RED and

BLACK wire coming from anemometer and connecting at pins 15

and 5 respectively, voltage at these pins should be around

18

12Volts DC. If voltage is not 12 V then power supply card of

digitizer have problem. In this case digitizer needs to be replaced.

iii) Check voltage between Yellow(pin3) wire and black wire(pin 5)

with yellow as positive terminal, value should be varying around

-6Volts, if it is so then anemometer is OK, Digitizer have some

problem.

And if voltage is zero volts then anemometer has become faulty

and need to be replaced.

4. What if TEMPERATURE AND DEW POINT are not available?

If temperature is not displayed and all other parameters are displayed

then it is primarily may be problem of TT/RH sensor. Before declaring

temp sensor faulty following checks should be done:

i) Check connections at field site.

ii) Check proper colour code wire is connected at proper pin of

digitizer.

iii) Check voltage at pins 19 and 21 of digitizer, it should be 12 volts DC,

if it is not then digitizer power card have a problem.

5. Temperature displayed is different from current temperature.

In this case go field site and clean the temperature sensor and it cap so

that proper air flow takes place. This may solve the problem.

6. Pressure data is not available.

If pressure data is not available check all connections of pressure sensor.

Also check the voltage at pin no 31 and 26, it should be around 12 Volt

DC.

7. NO data is displayed in Data Logger i.e. at MBR but data is available at

digitizer at field site. What could be the problem?

For this case to check the problem go step by step

i) Take the data logger to field site and connect directly with digitizer

via RS232 cable at COM3 ports. If data is available in data logger

then data logger is ok else it is faulty.

ii) Now if communication is via cable modems, if data logger is ok and

data is not available then cable modem is faulty. It needs to be

replaced.

iii) If communication is via Wi-Fi modem, check the signal strength in

the modem, if it is green light and WLAN LED is blinking then

19

modem is ok. If no light glows then modem is faulty. If red or

yellow light glows it means line of site is not clear.

iv) To check serial to Ethernet convertors, check TD/RD LED is blinking

or not. If convertors are ok then TD LED will blink at transmission

site and RD site will blink at receiver site. If there is no point of

RD/TD in convertor then check power LED is glowing or not . Also

check the LED is glowing or not when Ethernet cable is connected.

8. Display is not clearly visible or it is overlapping.

For this just switch off the system for few minutes and start it.

9. Slave display not working.

Bring the slave display and connect it directly with data logger via RS422

cable, if data is displayed it means display is ok. Then check the cable

connectivity from data logger to display unit it may be broken or

disconnected somewhere. If no data is displayed slave display have a

problem and need to be replaced.

10. Is earthing required for CWIS/DIWE?

Earthing is very necessary for all airport instruments. Lightning arrestor

should be within 10 meters of instrument and its height should be more

than wind sensor height.

20

7 . CONNECTIONS OF 10k SERVOPOT AND NORTH SETTING

WIND VANE

1. 10 K Servo pot terminal A and C are shorted, then one wire is taken

from one of the shorted terminals(terminal A in picture) and other wire

is taken from terminal B. see picture below

2. Fix the servo pot in the base of wind vane assembly with the help of

three clamps.

3. Now loose the direction rod ring (E,S,W,N) for the rotation by screw

driver.

4. Align NORTH direction rod with maximum resistance of servo pot(max

resistance is approx 10K ohm)

5. Tight the aligned North direction rod with max. resistance of servo pot.

6. Check the resistance with direction of E=2.5k ohm, S=5.0k ohm, W= 7.5k

ohm , N = 10 K ohm.

7. Tighten the screws of direction rod ring of Windvane .

8. Connect to DIWE logger pins as described in section 1.2.

21

7. ROUTINE OPERATING PROCEDURES:

1. Field site should be visited every fortnightly and site inspection should

be done.

2. Cleaning of MET area surrounding the instrument must be cleaned like

grass cutting every three months or before if required.

3. Temperature sensor cap should be cleaned every month for proper and

accurate readings.

4. All connections should be checked regularly.