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Campbell SR50AT, Instruction Manual

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Appendix D.  RS-232 and RS-485 Operation 

D-2

TABLE D-1.  SR50AT RS-232 Interface Wiring 

SR50AT 

Wire Colo

u

r 

Function 

Wiring Location 

Red 

+12 Vdc Power

Power Source (Datalogger: 

12V

) 

Black 

Power Ground 

System Ground and/or RS-232 

Receiver Ground (Datalogger: 

G

) 

Green 

RS-232 

(SR50AT 

Output) 

Pin 2 [RXD] (9-pin RS-232 Interface 

Connector: pn 

#

28840) 

White 

RS-232 

(SR50AT Input) 

Pin 3 [TXD] (9-pin RS-232 Interface 

Connector: pn 

#

28840) 

Clear 

Shield 

G

 (datalogger) 

Jumper Wire 

Pin 5 [

G

] (9-pin RS-232 Interface 

Connector: pn 

#

28840) 

TABLE D-2.  SR50AT Datalogger COM Port Wiring 

SR50AT Wire 

Colo

u

r 

Function 

CR1000 

CR6 

Red 

+12 Vdc Power

12V 

12V 

Black 

Power Ground 

G 

G 

Green 

RS-232 

(SR50AT Output) 

RX (

COM1

–

COM4

) 

RX (

COM1

–

COM2

) 

White 

RS-232 

(SR50AT Input) 

TX (

COM1

–

COM4

) 

TX (

COM1

–

COM2

) 

Clear 

Shield 

G 

G 

D.2  RS-485 Operation

The SR50AT sensor comes from the factory with the internal jumpers set to 

SDI-12 mode. To use the SR50AT in the RS-485 mode of operation, the 

jumpers need to be set as outlined in Appendix 

C

, 

Jumper Settings

 

(p. C-1)

. 

Complete RS-485 CRBasic programs can be found in Appendix 

B.3

, 

RS-485 

Example Programs

 

(p. B-8)

. 

The RS-485 on the SR50AT supports half-duplex communications, which 

means the SR50AT can receive and transmit data, but not simultaneously. 

Normally a master-slave relationship is used in most systems to avoid 

collisions between transmissions. For this reason, the 

Auto Measure Output

 is 

not recommended for RS-485 communications. It is much better to have a 

master initiate the communications by using the 

Measure On Poll

 or the 

Auto 

Measure Polled Output 

modes. 

You can use Campbell Scientific’s MD485 interface to connect one or more 

SR50AT sensors in RS-485 mode to an RS-232 device. This can be useful for 

Summary of Contents for SR50AT

Page 1: ...INSTRUCTION MANUAL SR50AT SR50AT 316SS and SR50ATH Sonic Ranging Sensors 10 16 C o p y r i g h t 2 0 0 7 2 0 1 6 C a m p b e l l S c i e n t i f i c I n c ...

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Page 3: ...s under guarantee or not Please state the faults as clearly as possible and if the product is out of the guarantee period it should be accompanied by a purchase order Quotations for repairs can be given on request It is the policy of Campbell Scientific to protect the health of its employees and provide a safe working environment in support of this policy a Declaration of Hazardous Material and De...

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Page 5: ...s digital cell phones and aerials may also not be applicable according to your locality Some brackets shields and enclosure options including wiring are not sold as standard items in the European market in some cases alternatives are offered Details of the alternatives will be covered in separate manuals Part numbers prefixed with a symbol are special order parts for use with non EU variants or fo...

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Page 7: ...fore beginning work Wear a hardhat and eye protection and take other appropriate safety precautions while working on or around tripods and towers Do not climb tripods or towers at any time and prohibit climbing by other persons Take reasonable precautions to secure tripod and tower sites from trespassers Use only manufacturer recommended parts materials and tools Utility and Electrical You can be ...

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Page 9: ...7 1 3 Mounting Options 8 7 2 SDI 12 Wiring 10 7 3 SDI 12 Programming 11 7 3 1 SDI12Recorder Instruction 11 8 Operation 11 8 1 Quality Numbers 12 8 2 Temperature Compensation 12 8 3 SDI 12 Measurements 14 8 3 1 SDI 12 Addresses 14 8 3 2 SDI 12 Commands 14 9 Maintenance and Troubleshooting 16 9 1 Disassembly Assembly Procedures 16 9 2 Data Interpretation and Filtering 19 9 2 1 Data Interpretation 19...

Page 10: ... Auto Output Mode D 7 D 3 3 3 Auto Measure Polled Output Mode D 7 D 4 4 Distance to Target or Depth D 8 D 4 5 Distance to Ground D 8 D 4 6 Measurement Interval Units D 8 D 4 7 Measurement Interval Value D 8 D 4 8 Output Unit D 9 D 4 9 Quality Output D 9 D 4 10 Diagnostics Output D 9 D 5 Serial Commands D 9 D 5 1 Setup Command D 9 D 5 2 Poll Command D 9 D 5 3 Information Command D 9 D 5 4 Temperatu...

Page 11: ...onfiguration Utility D 5 D 4 SR50AT Setup Menu D 5 E 1 Tera Term New Connection E 1 E 2 Setup Selections E 2 E 3 Terminal Configuration E 2 E 4 Windows Setup Changes E 3 E 5 Setting the Font Size E 3 E 6 Configuring the Serial Port E 4 E 7 Testing the Configuration E 4 E 8 Configuring the Com Port to Send an Operating System E 6 E 9 Jumper Settings E 6 F 1 SR50ATH Heater Option F 2 F 2 Complete Tr...

Page 12: ...gram B 1 B 2 CR6 SDI 12 Program B 3 B 3 CR1000 RS 232 Program B 5 B 4 CR1000 Programming Example Using an MD485 and SC110 9 pin Male Connector B 9 B 5 CR6 RS 485 Programming Example B 12 B 6 CR1000 Heater Program Example B 15 B 7 CR6 Heater Program Example B 18 ...

Page 13: ...his manual provides information only for CRBasic dataloggers It is also compatible with our retired Edlog dataloggers For Edlog datalogger support contact Campbell Scientific 2 Precautions READ AND UNDERSTAND the Safety section at the front of this manual Never open the sensor while it is connected to power or any other device Always disconnect the sensor using the connector or disconnect the cabl...

Page 14: ...r wiring terminals Short Cut is available as a download on www campbellsci eu and the ResourceDVD It is included in installations of LoggerNet PC200W PC400 or RTDAQ Use the following procedure to get started 1 Open Short Cut Click New Program 2 Select Datalogger Model and Scan Interval 60 second or higher scan interval is recommended Click Next ...

Page 15: ... changed by clicking the Unit of measure box and selecting cm ft or in Enter the Distance to base which is the distance from the SR50AT s wire mesh face to the ground SDI 12 Address defaults to 0 Enter the correct SDI 12 Address for the SR50AT if it has been changed from the factory set default value 4 After selecting the sensors click Wiring Diagram to see how the sensor is to be wired to the dat...

Page 16: ...ensors are capable of picking up small targets or targets that are highly absorptive to sound such as low density snow They use a unique echo processing algorithm to help ensure measurement reliability If desired these sensors can also output a data value indicative of measurement quality The SR50AT series sensors meet the stringent requirements of snow depth measurement that make them well suited...

Page 17: ...ments 1 2 s typical for SDI 12 measurements Selectable Outputs SDI 12 version 1 3 RS 232 1200 to 38400 bps RS 485 1200 to 38400 bps Measurement Range 0 5 to 10 m 1 6 to 32 8 ft Accuracy 1 cm 0 4 in or 0 4 of distance to target whichever is greater Accuracy specification excludes errors in the temperature compensation An external temperature compensation is required for the SR50AT Resolution 0 25 m...

Page 18: ...subject to the following two conditions 1 This device may not cause harmful interference 2 This device must accept any interference received including interference that may cause undesired operation View the EU Declaration of Conformity at www campbellsci eu sr50at www campbellsci eu sr50at 316ss www campbellsci eu sr50ath 1 Power supply must not drop below 11 0 V or heavier gage wire is required ...

Page 19: ...dius in the same measurement units as the CONEheight FIGURE 7 1 Beam Angle Clearance 7 1 2 Mounting Height Mount the SR50AT so that the face of the transducer is at least 50 cm 19 7 in away from the target However mounting the sensor too far from the target can increase the absolute error For example if your sensor is measuring snow depth in an area that will likely not exceed 1 25 m 4 1 ft then a...

Page 20: ...g kit attaches directly to the crossarm or pipe FIGURE 7 3 and FIGURE 7 4 shows the SR50AT mounted to a crossarm using the 19517 A U bolt mounts the bracket to the crossarm and two screws fasten the SR50AT to the bracket The 19484 mounting stem FIGURE 7 5 attaches to the crossarm using the 17953 Nu Rail fitting FIGURE 7 6 CM220 right angle mount CM230 adjustable angle mount or CM230XL extended adj...

Page 21: ...es Sonic Ranging Sensors 9 FIGURE 7 4 SR50AT 316SS Mounted to a Crossarm via the 19517 Mounting Kit with the Temperature Sensor Housed in a RAD06 Radiation Shield FIGURE 7 5 SR50AT Mounted to a 19484 Mounting Stem ...

Page 22: ...ion Wire Colour Wire Function Datalogger Connection Terminal Black Power Ground G Red Power 12V Green SDI 12 signal Control Port1 or U configured for SDI 122 White Ground G Clear Shield G 1 Dedicated SDI 12 port on CR5000 2 U channels are automatically configured by the measurement instruction To use more than one probe per datalogger either connect the different sensors to different terminals on ...

Page 23: ...2Recorder Instruction The SDI12Recorder measurement instruction programs CRBasic dataloggers CR200 X series CR300 series CR6 series CR800 series CR1000 CR3000 and CR5000 to measure the sensor This instruction sends a request to the sensor to make a measurement and then retrieves the measurement from the sensor See Section 8 3 SDI 12 Measurements p 14 for more information When using a CR200 X the S...

Page 24: ...measurements Zero indicates that the reading was not obtained Numbers greater than 300 indicate a degree of uncertainty in the measurement Causes of high numbers include sensor is not perpendicular to the target surface target is small and reflects little sound target surface is rough or uneven target surface is a poor reflector of sound extremely low density snow TABLE 8 1 Quality Number Descript...

Page 25: ...mmand makes it possible for the SR50AT to function as an SDI 12 temperature sensor If the internal SR50AT temperature correction needs to be bypassed the temperature output setting will need to be turned off for RS 232 and RS 485 modes Using measurement commands M M1 M5 and M6 in SDI 12 mode will not use the SR50AT probe to compensate for the speed of sound The compensation will then need to be do...

Page 26: ...ress If additional control ports are not available then the address will need to be changed To change the address of a sensor that has the default address of 0 to the address of 1 the following command can be sent 0A1 Only one sensor of the same address should be connected when using the change address command 8 3 2 SDI 12 Commands The SDI 12 protocol supports the SDI 12 commands listed in TABLE 8...

Page 27: ...surement Command Distance Meters D aCn Concurrent Measurements Same as M1 M8 Output is the same as M1 M8 aCC aCCn Concurrent Measurement Commands with Checksum See aM and aM1 aM8 Output is the same as aM aM1 aM8 Checksum is added aD0 Send Data Dependent upon command sent aV Verification command S1 S2 V WD S1 Firmware Signature S2 BootRom Signature V Supply Voltage WD Watch Dog Errors aI Send Ident...

Page 28: ...nt condensing humidity Regularly inspect the desiccant and if required replace it Desiccant capable of absorbing moisture is blue Once the desiccant becomes saturated the color changes from blue to pink In humid environments replace the desiccant more frequently Inspection or replacement of the desiccant requires the SR50AT to be disassembled Section 9 1 Disassembly Assembly Procedures p 16 Replac...

Page 29: ...SR50AT Series Sonic Ranging Sensors 17 FIGURE 9 1 Disconnect Cable from Sensor FIGURE 9 2 Remove Six Screws from the Transducer Housing ...

Page 30: ...SR50AT Series Sonic Ranging Sensors 18 FIGURE 9 3 Remove Transducer Housing and Disconnect Wires FIGURE 9 4 Location of Desiccant in Transducer Housing Assembly ...

Page 31: ...e the Two Flat Phillips Screws to Expose the PCB Carefully reassemble in reverse order 9 2 Data Interpretation and Filtering 9 2 1 Data Interpretation Although not common the SR50AT can occasionally output invalid reading indicators if it was unable to obtain a measurement For distance to target ...

Page 32: ... target When the echoes are weak the sensor also automatically increases sensitivity This makes the sensor more prone to the occasional erroneous reading from flying debris drifting snow or mounting hardware just outside the beam angle The reason not to average values is that occasionally a number with a very high error value is produced skewing the average The value should be ignored and not aver...

Page 33: ...and exit Short Cut Make note of the file name used when saving the Short Cut program 2 Open CRBasic Editor 3 Click File Open Assuming the default paths were used when Short Cut was installed navigate to C CampbellSci SCWin folder The file of interest has the CR2 CR300 CR6 CR8 CR1 CR3 or CR5 extension Select the file and click Open 4 Immediately save the file in a folder different from C Campbellsc...

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Page 35: ...ce value will be restored A control flag is used to initiate the SR50AT measurement cycle This allows for manual control in the field to check distances without waiting for the correct time interval to occur It is also used by the datalogger to initiate an automated measurement cycle Every measurement cycle is composed of 11 individual measurements that are spatially sorted to eliminate any low or...

Page 36: ...able Daily True 1 DataInterval 0 1440 Min 10 Minimum 1 BattV FP2 False False Maximum 1 BattV FP2 False False Minimum 1 PnlTmp_C FP2 False False Maximum 1 PnlTmp_C FP2 False False EndTable DataTable Hour True 1 DataInterval 0 60 Min 10 Sample 1 AirTempC FP2 Sample 1 TCDT IEEE4 Sample 1 Q FP2 EndTable PreserveVariables Main Program BeginProg Main Scan n 1 Scan 10 Sec 1 0 Battery Voltage measurement ...

Page 37: ...struction is used to store the initial distance in non volatile memory If power is lost at the site the initial distance value will be restored A control flag is used to initiate the SR50AT measurement cycle This allows for manual control in the field to check distances without waiting for the correct time interval to occur It is also used by the datalogger to initiate an automated measurement cyc...

Page 38: ...the SR50AT to the ground Public SR50AT_MID As Boolean Dim n used as a counter Define Data Tables DataTable Daily True 1 DataInterval 0 1440 Min 10 Minimum 1 BattV FP2 False False Maximum 1 BattV FP2 False False Minimum 1 PnlTmp_C FP2 False False Maximum 1 PnlTmp_C FP2 False False EndTable DataTable Hour True 1 DataInterval 0 60 Min 10 Sample 1 AirTempC FP2 Sample 1 TCDT IEEE4 Sample 1 Q FP2 EndTab...

Page 39: ... 1 TABLE B 2 Wiring for CR1000 and CR6 RS 232 Example Programs Wire Color Sensor Wire Description CR1000 Wire Channels CR6 Wire Channels Red Power source 12V 12V White SR50AT RX C1 C1 Green SR50AT Tx C2 C2 Black Ground G G Shield Shield Earth ground B 2 1 CR1000 RS 232 Program CRBasic Example B 3 CR1000 RS 232 Program CR1000 Series Datalogger Program SR50AT_RS232_FILTER CR1 This program contains a...

Page 40: ...e stored Public SR50ATCtrl As Boolean Set this flag to measure and store the initial distance from the SR50A to the ground Public SR50AT_MID As Boolean Declare SR50AData as a dimensioned string of maximum 50 chrs Public SR50ATData As String 50 Values returned from the SR50AT Public ParseValsT 6 As Float Alias ParseValsT 1 SerialAddressT Units SerialAddressT addr Alias ParseValsT 2 Dist_To_SurfaceT...

Page 41: ...e C1 and C2 for RS232 communication 9600 BAUD is the default SerialOpen Com1 9600 0 0 200 Scan 10 Sec 1 0 Battery Voltage measurement BattV Battery BattV Wiring Panel Temperature measurement PnlTmp_C PanelTemp PnlTmp_C _60Hz Automated snow depth measurement Must occur two minutes before actual storage time to get 11 measurements completed If TimeIntoInterval 58 60 Min Then SR50ATCtrl True EndIf Se...

Page 42: ...nostic counters after Daily_Status table is stored If Daily Output 1 1 Then ROM_Cntr 0 SR50AT_WtchDg_Cntr 0 EndIf NextScan EndProg B 3 RS 485 Example Programs Detailed information using RS 232 and RS 485 is provided in Appendix D RS 232 and RS 485 Operation p D 1 B 3 1 CR1000 Programming Example Using an MD485 and SC110 9 pin Male Connector For this example an MD485 is used to convert the SR50AT R...

Page 43: ...ue from the SR50AT head to the ground is measured by setting the flag SR50AT_MID to TRUE Set this flag after installing the SR50AT in the field Setting this flag will initiate a measurement cycle and the resulting value stored as the initial distance The initial distance is used to calculate snow depth The PreserveVariables instruction is used to store the initial distance in non volatile memory I...

Page 44: ...lias ParseValsT 4 SR50AT_Temp Units SR50AT_Temp C Alias ParseValsT 5 DiagnosticsT Units DiagnosticsT value Alias ParseValsT 6 ChcksumT Units ChcksumT value SR50AT diagnostic counters Values are incremented if an error occurs Public ROM_Cntr Units ROM_Cntr value Public SR50AT_WtchDg_Cntr Units SR50AT_WtchDg_Cntr value Dim scratch Array to hold 11 SR50AT measurements composed of a distance and quali...

Page 45: ...urements completed If TimeIntoInterval 58 60 Min Then SR50ATCtrl True EndIf Set this flag to true to get the initial distance from the SR50AT to the ground If SR50AT_MID Then SR50ATCtrl True Logic to make 11 snow depth measurements sort them and store the corrected values If SR50ATCtrl Then Transmit serial command p33 CR SerialOut Com1 POLL_A 0 0 Flush the serial buffer SerialFlush Com1 Recieve se...

Page 46: ...he SR50AT in the field Setting this flag will initiate a measurement cycle and the resulting value stored as the initial distance The initial distance is used to calculate snow depth The PreserveVariables instruction is used to store the initial distance in non volatile memory If power is lost at the site the initial distance value will be restored A control flag is used to initiate the SR50AT mea...

Page 47: ...osticsT value Alias ParseValsT 6 ChcksumT Units ChcksumT value SR50AT diagnostic counters Values are incremented if an error occurs Public ROM_Cntr Units ROM_Cntr value Public SR50AT_WtchDg_Cntr Units SR50AT_WtchDg_Cntr value Dim scratch Array to hold 11 SR50AT measurements composed of a distance and quality number and air temperature Public SR50AT 11 3 Sorted array of 11 SR50AT measurements compo...

Page 48: ... Then SR50ATCtrl True EndIf Set this flag to true to get the initial distance from the SR50AT to the ground If SR50AT_MID Then SR50ATCtrl True Logic to make 11 snow depth measurements sort them and store the corrected values If SR50ATCtrl Then Transmit serial command p33 CR SerialOut ComC1 POLL_A 0 0 Flush the serial buffer SerialFlush ComC1 Recieve serial string from SR50A SerialIn SR50ATData Com...

Page 49: ... C1 White Not used G G Black Ground G G Shield Shield Earth ground G G SR50ATH Heater Power Cable Wire Colour Heater Wire Description CR1000 Wire Channels CR6 Wire Channels Black Power source SW 12 SW12 1 White Power ground G G Shield Shield Earth ground CRBasic Example B 6 CR1000 Heater Program Example CR1000 Program SR50ATH_SDI12_FILTER CR1 This program contains a number of features not found in...

Page 50: ...s Quality number Alias SR50AT_M 3 MAir Units MAir C Air temperature Array to hold 11 SR50AT measurements composed of a distance and quality number and air temperature Public SR50AT 11 3 Sorted array of 11 SR50AT measurements composed of a distance and quality number and temperature Measurements are sorted by the distance value from smallest to largest Public Result_SR50AT 11 3 Public TCDT Units TC...

Page 51: ...rt them and store the corrected values If SR50ATCtrl Then SR50AT Sonic Ranging Sensor SDI 12 Output measurements MDT MQ MAir SDI12Recorder SR50AT_M 1 0 M3 1 0 Load the array to be sorted SR50AT n 1 SR50AT_M 1 SR50AT n 2 SR50AT_M 2 SR50AT n 3 SR50AT_M 3 n 1 If n 11 Then n 1 SR50ATCtrl False SortSpa Result_SR50AT 1 1 11 SR50AT 1 1 2 TCDT Result_SR50AT 6 1 Q Result_SR50AT 6 2 AirTempC Result_SR50AT 6...

Page 52: ...alogger SW12 line to power the heater Battery voltage must be greater than 11 7vdc and the air temperature must be less than or equal to 2 C to power the heater PipeLineMode Declare Variables and Units Public BattV Units BattV Volts CR1000 battery voltage Public PnlTmp_C Units PnlTmp_C C CR1000 panel temperature Public HtrCntrl As Boolean Single measured values Public SR50AT_M 3 Alias SR50AT_M 1 M...

Page 53: ...pth measurement Must occur two minutes before actual storage time to get 11 measurements completed If TimeIntoInterval 58 60 Min Then SR50ATCtrl True EndIf Set this flag to true to get the initial distance from the SR50AT to the ground If SR50AT_MID Then SR50ATCtrl True Logic to make 11 snow depth measurements sort them and store the corrected values If SR50ATCtrl Then SR50AT Sonic Ranging Sensor ...

Page 54: ...e 11 7 vdc and the air temperature less than 2 C to turn on the heater If BattV 11 7 Then If AirTempC 2 Then HtrCntrl True If AirTempC 3 Then HtrCntrl False Else HtrCntrl False EndIf SW12 1 HtrCntrl Call Data Tables and Store Data CallTable Daily CallTable Hour NextScan EndProg ...

Page 55: ... jumpers on one group at a time Never install more than three jumpers and never mix the jumpers among the SDI 12 RS 232 or RS 485 locations The other jumper located on the SR50AT places the sensor in either the normal operation mode or in the program update mode The program mode is only used for updating the internal firmware of the sensor During operation have the jumper in the RUN position Refer...

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Page 57: ... 1 RS 232 Wiring FIGURE D 1 and TABLE D 1 show wiring for the SR50AT in RS 232 mode The ground used with the RS 232 connector pin 5 must use the same ground as the SR50AT For the example below the power for the SR50AT is coming from the datalogger A jumper wire is used from the RS 232 connector s pin 5 to the datalogger ground FIGURE D 1 RS 232 DB9 Connector Description RS 232 Female DB9 Connector...

Page 58: ...Shield G G D 2 RS 485 Operation The SR50AT sensor comes from the factory with the internal jumpers set to SDI 12 mode To use the SR50AT in the RS 485 mode of operation the jumpers need to be set as outlined in Appendix C Jumper Settings p C 1 Complete RS 485 CRBasic programs can be found in Appendix B 3 RS 485 Example Programs p B 8 The RS 485 on the SR50AT supports half duplex communications whic...

Page 59: ... Wiring Using a MD485 TABLE D 3 and FIGURE D 2 show the wiring for the SR50AT in RS 485 mode TABLE D 3 Connections for RS 485 Mode Colour Function Connection Black Power Ground System Ground and or RS 232 Receiver Ground Pin 5 of a computer DTE DB 9 connector Red Power Power Source 12V Green RS 485 A MD485 RS 485 A Terminal White RS 485 B MD485 RS 485 B Terminal Clear Shield Shield Earth Ground FI...

Page 60: ... E 1 The following settings apply to Device Configuration Utility or any program used for communications Baud Rate Current SR50AT SettingNote Data Bits 8 Parity None Stop Bits 1 Flow Control None Local Echo On The factory default baud rate is 9600 bps Once the baud rate is changed the new baud rate must be used for further communications to the SR50AT Ensure to keep track of the baud rate setting ...

Page 61: ... 3 Initial Terminal Window in Device Configuration Utility To enter Setup mode type setup in the terminal window and press the Enter key The word setup and all options in the setup menu are not case sensitive The SR50AT should respond with the setup menu shown in FIGURE D 4 FIGURE D 4 SR50AT Setup Menu ...

Page 62: ... Interval Units Seconds Minutes Hours Seconds Measurement Interval Value Integer 1 255 60 Output Unit Metres Centimetres Millimetres Feet Inches Metres Setting Description Options Default Value Quality Output On Off Off Change this to ON Temperature Output On Off Off Output valid only for the SR50ATT Diagnostics Output On Off Off Change this to ON D 4 1 Baud Rate Setting The factory default baud r...

Page 63: ...R50AT immediately begins a measurement and transmits the resulting data packet when the measurement is complete Typically the SR50AT transmits the data packet within 1 second of receiving the command packet The SR50AT only performs a measurement when requested The data output will lag the measurement command by 1 second This configuration is conducive to a multidrop RS 485 system where individual ...

Page 64: ...must be in meters regardless of the output units that are selected If the exact value cannot be obtained it is better to slightly overestimate the value rather than underestimating it If a Distance to Ground value is too small the SR50AT will output an error value as the snow surface should not be below the ground surface D 4 6 Measurement Interval Units This setting is only applicable if either t...

Page 65: ...or s settings Upper and lower case letters are accepted and a carriage return character must also terminate the string setup CR D 5 2 Poll Command The poll command is used to obtain the sensor s output values The poll command consists of the upper or lower case letter p followed by the SR50AT address default 33 The command must also terminate with a carriage return character pAA CR where AA is a t...

Page 66: ... degrees C t33 tt ttt CR Temperature command with factory address of 33 and a temperature value in Celsius D 6 RS 232 RS 485 Data Output Format D 6 1 Measurement Output The measurement output string for the SR50AT is as follows STX aa D DDD QQQ TT TT VVVVV CC CR LF ETX STX is the hex character h02 2 in decimal aa These two characters are the serial address of the sensor The default is 33 Note this...

Page 67: ...urred VVXXX The three digits XXX are for factory use and should always read 111 CC This is a two character checksum of the data packet The checksum is the two s complement of the data packet sum including control characters The Least significant byte is used resulting in a two character checksum STX h02 Hexadecimal CR h0D Hexadecimal LF h0A Hexadecimal ETX h03 Hexadecimal The following is a sample...

Page 68: ... WWWWW This is the checksum of the firmware CC This is a two character checksum of the data packet The checksum is the two s complement of the data packet sum including control characters The least significant byte is used resulting in a two character checksum STX h02 hexadecimal CR h0D hexadecimal LF h0A hexadecimal ETX h03 hexadecimal The following is a sample packet with proper checksum STX 33 ...

Page 69: ...eleases E 1 Configure Tera Term for Serial 9600 BPS Communication 1 Click on the Tera Term icon and bring up the software Tera Term always starts up with the New connection window as shown in FIGURE E 1 a Click on the radio button next to Serial b Click on the down arrow to the far right of Port and pick the COM port you are using to communication with the SR50AT T COM port 4 is used in the exampl...

Page 70: ... 2 Setup Selections 3 Select Terminal from the drop down menu list in Setup The SR50AT T does not echo characters sent to it To see what you re typing Local Echo needs to be switched on by checking the box next to Local Echo FIGURE E 3 Leave everything else at the default settings Click on the OK button to save the settings or the Cancel button to simply exit FIGURE E 3 Terminal Configuration ...

Page 71: ...aracters on a white background To change the settings click the radio button next to Background and click on the Reverse button Click on the OK button when finished making changes See FIGURE E 4 FIGURE E 4 Windows Setup Changes 5 By default Tera Term uses a font size of 9 If a larger font size is desired select Font from the drop down list in Setup Under Size select the desired font size FIGURE E ...

Page 72: ...d FIGURE E 6 FIGURE E 6 Configuring the Serial Port 7 All changes needed to work with the SR50AT T are complete You are back at the main screen with the cursor blinking in the upper left corner of the window To see if communication has been established with the SR40A T type setup and press enter The word setup should appear in the terminal window and the SR50AT T setup window should appear as well...

Page 73: ...mware Update E 2 1 Configure Tera Term to Send SR50AT T Firmware Update Device Configuration Utility cannot be used to send a firmware update to a SR50AT T General setup requires the following COM port configuration BAUD rate 38400 Data Bits 8 Parity None Stop Bits 1 Flow Control XON XOFF 25 ms line delay 1 To configure Tera Term follow steps 1 through 3 from Appendix E 1 Configure Tera Term for S...

Page 74: ...er For this example the file SR50AT_May_29_2007_V_1_3 TXT will be sent to a SR50ATT This firmware update is used for either the SR50AT or SR50ATT To send a firmware update to the SR50AT T the jumpers must be configured for RS 232 operation and the jumper moved from RUN to PROG See FIGURE E 9 below FIGURE E 9 Jumper Settings Firmware updates should only be performed at an appropriate workstation wi...

Page 75: ...k holes in the disk assembly Set the two screws aside f The bottom disk assembly and the transducer housing have a V shaped notch that lines up with a mating V in the metal housing Separate the bottom disk from the main metal housing g The circuit board will remain connected to the housing via the signal wires h Place the bottom disk circuit assembly on the work bench with the circuit board and DB...

Page 76: ...ocess is occurring in Tera Term Directly above the Send File window you will see the lines of code being sent to the SR50AT T Do not click on any of the buttons in the Send File window The window will automatically disappear after the file has been sent The green light on the SR50AT T will continue to flash for several minutes after the file has been sent When the new firmware is loaded and operat...

Page 77: ...ps screws back in the countersunk holes Do not over tighten the screws They should be snug b Older transducer heads use a removable O ring Carefully seat the O ring back into place and make sure you won t cut it when assembling the transducer assembly c Line up the connector on the transducer housing with the mating connector on the disk circuit assembly and slide it into place until the tab click...

Page 78: ...Appendix E Tera Term QuickStart E 10 ...

Page 79: ...g to reduce power requirements The heater power must be turned off when operating at temperatures of 25 C or more CRBasic programs that control the heater are provided in Appendix B 4 Heater Program Examples p B 15 F 1 Heater Specifications Heater Resistance 75 Ω Nominal Operating Voltage 12 V ac or dc use a properly conditioned low noise power source A noisy power source will affect operation of ...

Page 80: ...ansducer and desiccant replacement is slightly different for the SR50ATH When ordering replacement transducers ensure that the Replacement Transducer Maintenance Kit pn 32571 is ordered The procedure to disassemble the SR50ATH for desiccant replacement or transducer replacement is as follows 1 Remove the six Phillips screws on the outermost hole pattern The screws used on the SR50AT have changed f...

Page 81: ...e old packets to be removed for replacement During reassembly ensure that the desiccant does not come in contact with the metal backing of the transducer If only the desiccant is being inspected or replaced steps 4 and 5 are not required Steps 4 to 6 are required to replace the transducer only 4 Your transducer kit comes with a replacement for the O ring that seats between the main sensor body and...

Page 82: ...le pattern as shown 6 Replace the transducer assembly and the second O ring that seats under the transducer assembly 7 Reassemble the sensor in the reverse order Please observe the orientation of the parts wiring and desiccant FIGURE F 2 Complete Transducer Assembly with Power Connection ...

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Page 84: ...Rua Apinagés nbr 2018 Perdizes CEP 01258 00 São Paulo SP BRASIL www campbellsci com br vendas campbellsci com br Campbell Scientific Canada Corp 14532 131 Avenue NW Edmonton AB T5L 4X4 CANADA www campbellsci ca dataloggers campbellsci ca Campbell Scientific Centro Caribe S A 300 N Cementerio Edificio Breller Santo Domingo Heredia 40305 COSTA RICA www campbellsci cc info campbellsci cc Campbell Sci...

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