Data Signals and Data Signals and CollectionCollection

Data TypesData Types

• 2 types of output2 types of output– AnalogueAnalogue

• Usually raw signalUsually raw signal• Raw VoltageRaw Voltage

– DigitalDigital• Usually a calibrated signalUsually a calibrated signal• RS-232 or RS-485RS-232 or RS-485

• Either way eventually it all needs to be Either way eventually it all needs to be digital for processingdigital for processing

What is my digital outputWhat is my digital output

• Communication typesCommunication types• SerialSerial• EthernetEthernet

• Data formatData format– Binary?Binary?– Hexadecimal?Hexadecimal?– ASCII? (decimal)ASCII? (decimal)

• For most cases this is the format you want to end up withFor most cases this is the format you want to end up with– If not ASCII how and I going to get it to ASCIIIf not ASCII how and I going to get it to ASCII

• Converter programConverter program– All companies proved a converter program for their sensors All companies proved a converter program for their sensors

datadata– Usually extract/convert data using datalogger programUsually extract/convert data using datalogger program

DataloggerDatalogger

• A datalogger is simply a device that record A datalogger is simply a device that record the data from a single or multiple sensors.the data from a single or multiple sensors.– Can be within the sensor or a separate deviceCan be within the sensor or a separate device– Some sensors act as datalogging “hubs”Some sensors act as datalogging “hubs”

•Record auxiliary sensors on top of their own Record auxiliary sensors on top of their own sensorssensors

– Example – SBE 19Example – SBE 19

• Different dataloggers take different signalsDifferent dataloggers take different signals

Datalogger ExamplesDatalogger Examples

• SBE CTD’s only takes SBE CTD’s only takes Analogue signalAnalogue signal– Exception is SBE 19 plus Exception is SBE 19 plus

V2 has one Digital inputV2 has one Digital input• Wetlabs DH4Wetlabs DH4

– Can be configured to Can be configured to costumer needscostumer needs

– Up to 8 Digital portsUp to 8 Digital ports– Up to 4 analogue portsUp to 4 analogue ports

• Other companies have Other companies have dataloggers you can dataloggers you can interface withinterface with– These are the two we have These are the two we have

at USMat USM

Questions for deciding what Questions for deciding what signal/sensor you needsignal/sensor you need

• WhatWhat– What data do you really needWhat data do you really need

•Calibrated ConcentrationCalibrated Concentration

oror

•Change in signalChange in signal– Calibration not neededCalibration not needed

Change only?Change only?

Calibrated ConcentrationCalibrated Concentration

• What concentration rangeWhat concentration range– Sensors are calibrated for different Sensors are calibrated for different

rangesranges•0-50ug/L or 0-500ug/L0-50ug/L or 0-500ug/L

• What type of Feature IdentificationWhat type of Feature Identification– MicroscaleMicroscale– MacroscaleMacroscale

Data RatesData Rates

• FrequencyFrequency– Hertz (Hz)Hertz (Hz)

• Cycles per secondCycles per second

• What can the What can the sensor do?sensor do?

• What can the What can the datalogger do?datalogger do?

http://en.wikipedia.org/wiki/Hertz

Black is Contros CO2 sensor with a response time ~ 1min

http://www.amloceanographic.com/Portals/0/Ref_Pics/Graphs/actual%20vs%20measured.jpg

Sample Rate vs Response Sample Rate vs Response timetime• Sample RateSample Rate

– The number of samples, or readings, The number of samples, or readings, persecond of an analogue signalpersecond of an analogue signal

• Response timeResponse time– Time a system takes to respond to a Time a system takes to respond to a

given inputgiven input•Time between software sending a message Time between software sending a message

and instrument sending a replyand instrument sending a reply

• Not always the same for some sensorsNot always the same for some sensors

What if your sample rate is not What if your sample rate is not what you need?what you need?

• Find a different sensorFind a different sensor– Not always easy with newer specialized Not always easy with newer specialized

sensorssensors•Not many companies making themNot many companies making them

• Talk to the company about modifying Talk to the company about modifying the sensorthe sensor– Ask for an analogue out and make your Ask for an analogue out and make your

own dataloggerown datalogger

How does the sensor send the How does the sensor send the datadata

• As soon as the sensor is powered onAs soon as the sensor is powered on

oror

• Need to interrogate the sensor for a Need to interrogate the sensor for a signal returnsignal return– If so what signal do you need to send itIf so what signal do you need to send it– Can your datalogger send signals or just Can your datalogger send signals or just

listenlisten•Commands are usually binary or hexadecimalCommands are usually binary or hexadecimal

ECO BB9 - Wetlabs

Will our sensor work?Will our sensor work?

• Read the Specifications for the Read the Specifications for the instruments and data loggerinstruments and data logger

Will our Sensor work?Will our Sensor work?

• Just because the specification do not Just because the specification do not show the output you need doesn’t show the output you need doesn’t mean the sensor is incapable of that mean the sensor is incapable of that output.output.– Talk to the companyTalk to the company

Sensor pin outsSensor pin outs

Wiring cablesWiring cables

DB9 Connector – Serial DB9 Connector – Serial CommsComms

• Pin 2 – RXPin 2 – RX

• Pin 3 – TXPin 3 – TX

• Pin 5 - GNDPin 5 - GND

Ordering plugsOrdering plugs

• What can you orderWhat can you order– PigtailsPigtails– Whole cablesWhole cables– Dummy plugsDummy plugs

• Don’t forget the locking collar!!Don’t forget the locking collar!!– Pigtails and Dummy plugsPigtails and Dummy plugs

• Every company makes the other Every company makes the other company cablescompany cables

How to order the correct How to order the correct cable?cable?

• www.impulse-net.comwww.impulse-net.com