CS725 Snow Water Equivalency Sensor Revision: 8/12 C o p y r i g h t © 2 0 1 0 - 2 0 1 2 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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Table of Contents PDF viewers: These page numbers refer to the printed version of this document. Use the PDF reader bookmarks tab for links to specific sections. 1. Introduction .................................................................1 2. Specifications .............................................................1 3. Wiring...........................................................................2 4. Connecting the CS725 to a Computer ......................2 5.
Table of Contents 13. Detailed Measurement Theory .................................29 14. Maintenance and Assembly .....................................31 15. Datalogger CRBasic Programming .........................33 15.1 15.2 Extended Data Output (.flla) Command............................................ 33 Short Form Data Output (.fs) Command ........................................... 36 4-1. 7-1. 9-1. 9-2. 9-3. 13-1. 14-1. 14-2. 14-3. 14-4. CS725 connection to DB9F-TERM ...........................
Cautions / Safety Notes • If you are unable to determine that your structure or mounting method is suitable for the CS725 sensor, please contact an expert or professional who can assist you in determining the structural mounting requirements for your installation of the CS725. • Always ensure that the collimator is secured to the structure with the long safety cable. • Do not disassemble the CS725 without consulting the factory first.
CS725 Snow Water Equivalency Sensor 1. Introduction The CS725 sensor is primarily designed to measure the SWE (Snow Water Equivalency) in a snow pack. The CS725 obtains a measurement by passively monitoring the attenuation of naturally existing electromagnetic radiation, due to the presence of potassium and thallium. As snow accumulates on top of the ground, the CS725 measures a decrease in the normal background radiation levels. The higher the water content, the higher the attenuation of the radiation.
CS725 Snow Water Equivalency Sensor 3. Coverage Beam Angle: 60° Operating Temperature: -40° to +40°C Maximum Cable Length: 30 m (95 ft) (9600 bps or less) Cable Type: 4 conductor, 2-twisted pair, 22 AWG, Santoprene jacket Dimensions (Without Collimator) Length: Diameter: 62 cm (24.4 in) 12.7 cm (5 in) Weight Main Body: Collimator: Total: 9.0 kg (20 lbs) 25 kg (55 lbs) 34 kg (75 lbs) Wiring The wiring for the CS725 connector-cable assembly is as follows: 4.
CS725 Snow Water Equivalency Sensor FIGURE 4-1. CS725 connection to DB9F-TERM When connecting the CS725 to a computer, a power source is required to power the CS725. A good quality regulated +12 Vdc power source should be used such as a bench power supply or a +12 Vdc battery. It is recommended to disconnect the cable from the CS725 while terminating the cable connections. After the connections are verified, the connector can be reconnected to the CS725. 5.
CS725 Snow Water Equivalency Sensor When the power is applied to the CS725 or the connector is plugged in, the CS725 will output the following message on the RS-232 port on power up: GMONIII Scionix 3x3 V4f_13u SN: 9999 Where: 6. GMONIII: Is the original sensor Identifier (now known as CS725) Scionix 3x3: Is the Gamma Detector Type V4f_13u: Is the Firmware Software Revision SN: 9999 Is the sensor’s serial number Communicating with the CS725 6.
CS725 Snow Water Equivalency Sensor The menus can be switched between English and French. To change the language setting, key the command .L. This will allow the selection of either English or French. The English version of the Main menu is as follows: *** LIST OF COMMANDS **** [.l] Language (French or English) [.h] Read the current live histogram [.hp] Display the K and Tl peak positions from the live histogram [.hl] Display the current histogram in log scale [.
CS725 Snow Water Equivalency Sensor 2. [.h] The [.h] command is used to obtain the current histogram results. This information would normally be used for diagnostics or by a user who requires an analysis of the gamma radiation spectrum. The counts for 1024 bin values are returned in this command. The format is as follows: 12 This line represents the counts for BIN#1 345 This line represents the counts for BIN#2 333 This line represents the counts for BIN#3 . . .
CS725 Snow Water Equivalency Sensor 4. [.hl] The [.hl] command is used to obtain a graphical representation of the current histogram results. This information would normally be used for diagnostics or by a user who requires an analysis of the gamma radiation spectrum. The command produces a log scale graph as follows: 5. [.hr] The [.hr] command is used to verify radiation counts in manual mode. The [.
CS725 Snow Water Equivalency Sensor -Elapsed time,current histo : 00:03:59 Pos K = 240.4; Pos Tl = 427.5; Cnt K = 003679.8; Cnt Tl = 000088.3; 6. [.a] The [.a] command is used to set the start and stop times for a specified measurement interval. This command could be used in the process to qualify a site for appropriate amounts of background radiation. This parameter is only made use of when the CS725 is in the manual mode. The CS725 is placed in in the manual mode by entering the Parameter menu [.
CS725 Snow Water Equivalency Sensor 9. [.dd] The [.dd] command is used to set the current date and time. The following menu is activated from the [.dd] command: Modify that date? : [1] aaaa: 2009 [2] mm: 09 [3] jj: 16 [4] hh: 15 [5] mm: 01 [6] ss: 54 [0] Exit [99] Accept selection To Modify: [parameter number, space, new value,CR] The current values at the time the .dd command was entered are displayed. To change a value, enter the parameter number followed by the new value and then the enter key.
CS725 Snow Water Equivalency Sensor 10. [.hd] The [.hd] command is used to read back histograms from EPROM according to selected dates. When the [.hd] command is entered, the following menu is displayed: Histograms: Select first day to retrieve Modify that date? : [1] aaaa: 2009 [2] mm: 09 [3] jj: 16 [.] Exit [99] Accept selection To Modify: [parameter number, space, new value,CR] This is the first day that the historic histograms will be displayed from.
CS725 Snow Water Equivalency Sensor 11. [.f] The [.f] command is used to read back measurement results from EPROM according to selected dates. Four lines will be output for every day requested where monitoring occurred. See the section under [.fl] for output details. The date selection procedure is the same as the [.hd] command. 12. [.fl] The [.fl] command is used to read back the current day readings, which can be up to four detailed measurement results.
CS725 Snow Water Equivalency Sensor 14. [.fs] The [.fs] command is used to read back last results in short form. The short form consists of the date and time of the readings and the SWE values in millimeters. The format is as follows: DD/MM/YYYY HH:MM:SS SWE_K SWE_TL 01/10/2009 06:59:50 123 129 15. [.p] The [.p] command is used to display the Parameter Setup menu.
CS725 Snow Water Equivalency Sensor [4] Delay after start of measure for data transmission (secs.) This defines the time at which the calculated results from the previous 24-hour period will be automatically transmitted from the serial port. It is recommended to set the value to zero in order to disable the automatic transmission of data via the serial port. This is in seconds after the start of the new 24-hour period. The minimum value should be 300 in order to allow the calculations to complete.
CS725 Snow Water Equivalency Sensor Once the soil is frozen, this quantity is relatively constant. The format is an integer between 1 and 150. [10] Estimated soil humidity in % weight (min: 1, max: 150) for HCalib mode This is a site-specific parameter used for the auto calibration of the CS725. The auto calibration mechanism calculates baseline values for the coefficients n0Ke and n0Tl.
CS725 Snow Water Equivalency Sensor [16] SN Threshold for the snow cover This parameter is a threshold above which the normal calculation of the SWE will be performed. The threshold is applied to a calculation of the SWE based on the ratio of K/Tl, which is independent of the humidity of the soil, but less accurate than the SWE measured from the K and Tl information independently. When the SWE calculated from the K/Tl ratio is reached, it is assumed that there is a snow cover.
CS725 Snow Water Equivalency Sensor humidity of the soil specified in the parameter HCalib. When this is done, the new values of n0Ke and n0Tl will be stored in the parameter block, and the operation mode will be changed internally by the CS725 to automatic (code = 0). The automatic mode (code =0) is the normal mode of operation. The CS725 will continuously cycle through 24-hour periods, calculating the SWE for the previous 24 hours at 6 hours intervals. 16. [.s] The [.
CS725 Snow Water Equivalency Sensor The file to retrieve will then be selected using the Hyper Terminal function. 19. [%Rhard][%Rboot] [%Rhard] restarts the software processor. [%Rboot] restarts the firmware and it has the same effect as a power off /power on. 20. [UU] [UU] CS725/Terminal synchronizing sequence for rates other than 9600 bauds The [UU] command synchronizes the baud rate of the CS725 to the terminal baud rate. 6.
CS725 Snow Water Equivalency Sensor CAUTION The collimator weighs 25 kg (55 lb). A long safety strap is also included for securing the collimator to the mounting structure once it is installed. FIGURE 7-1. CS725 components 8. Site Selection Details It is important to determine if the intended installation site of the CS725 will have appropriate sources of potassium and thallium to provide sufficient counts for the expected SWE.
CS725 Snow Water Equivalency Sensor It is reasonable to have small amounts of wood material within the 6 m clearance radius. Be aware that reducing the amount of material near the CS725 or increasing the distance will reduce its influence on the readings. 8.1 Collimator The need for a collimator is typically dictated by the characteristics of the intended site. The presence of wooded vegetation, man-made structures and the expected SWE for a given site are all a factor.
CS725 Snow Water Equivalency Sensor background levels of K and Tl counts, and moving the location may be required to improve the results from the CS725. Required equipment: • CS725 with accessories. • Suitable +12 Vdc power supply or battery to run the CS725 for several hours. • Suitable mounting mechanism to suspend the CS725 vertically over the ground at the qualifying site (with the collimator). For qualifying purposes, the distance above the ground is not critical.
CS725 Snow Water Equivalency Sensor • A delay will need to be typed in followed by the run time duration. It is recommended to run the test for 1 or 2 hours; a value of 1 second can be entered for the delay. A 1-hour test is 3600 seconds, so the following would be typed in “13600”. • The CS725 will now monitor the gamma radiation for an hour. • The .hr command can be issued several minutes into the test for verification that it is running properly. The .
CS725 Snow Water Equivalency Sensor TABLE 8-3. Thallium (Tl) Count Range Guideline 9. Count Range 24 Hour Tl Count Range 1 Hour Tl 0 to 9600 0 to 400 Insufficient Tl counts for CS725 SWE measurements. 9600 to 36000 400 to 1500 Useable Tl count range for CS725 SWE measurements. May experience larger errors for higher SWE values. 36000 to 48000 1500 to 2000 Good Tl count range for CS725 SWE measurements. Should maintain specified operating characteristics.
CS725 Snow Water Equivalency Sensor 9.1 Mounting Options FIGURE 9-1. Position of 1/4‐20 mounting holes The CS725 comes with mounting plates that can be used with the 27412 mounting kit and 27413 right-angle mounting kit to mount the sensor. The mounting plates contain four ¼-20 threaded holes for fastening the sensor to the 27413 or wall mount. Refer to FIGURE 9-1, Position of ¼-20 mounting holes, for details.
CS725 Snow Water Equivalency Sensor FIGURE 9-2. Example of wall/plate mounting It is possible to rotate the CS725’s main body with respect to the mounting plates. FIGURE 9-2, Example of wall/plate mounting, shows one of four fasteners that need to be loosened to rotate the main body. Ensure that the fasteners are not loosened too much to prevent the body from sliding through the mounting plates.
CS725 Snow Water Equivalency Sensor FIGURE 9-3. Horizontal pipe mounting shown with the 27412 Mount Kit A fully mounted CS725 with the 27412 mounting brackets is shown in FIGURE 9-3, Horizontal pipe mounting shown with the 27412 Mount Kit. 10. Final Parameter Setup Once the CS725 is installed, the following items are required for the final setup of the CS725. • Obtain the soil moisture values for the ground under the CS725. The recommended depth of the measurements for most soil types is 20 cm (8 in).
CS725 Snow Water Equivalency Sensor If the installation is being done with no snow present, then the following needs to be done to complete the setup: Access the Parameter menu of the CS725 via the terminal emulator by keying in the command [.p] [1] Station ID (Max 8 characters; ex: Gouin_21) [3] Time of start of measure (relative to GMON 00h RTC) [4] Delay after start of measure for data transmission (secs.
CS725 Snow Water Equivalency Sensor radiation count values seen in the detailed measurement data output string which can be accessed by typing the command [.fl]. 11. Firmware Update (using command .0xw) The firmware for the CS725 can be updated using the RS-232 serial communication interface. This can be accomplished by connecting the CS725 to a computer using the DB9F-TERM (see Section 4, Connecting the CS725 to a Computer).
CS725 Snow Water Equivalency Sensor After the memory is allocated (within 1 minute), the CS725 will prompt for the file transfer with the following message: Launch the file transfer with the Hyper Terminal If you are using HyperTerminal, select “Send Text File…” from the Transfer menu. The supplied programming file will need to be selected and sent to the CS725. The process will take approximately 5 minutes at 57600 bps and in excess of 30 minutes at 9600 bps.
CS725 Snow Water Equivalency Sensor 12. System Power Requirements and Recommendations 12.1 Non Solar-Powered Sites It is always recommended that the CS725 be operated from an uninterruptable power supply. Normally an AC charger is used to charge +12 Vdc batteries. For sites that operate this way, it is recommended that the batteries have the capacity to supply the system for a minimum of 48 hours. This should be increased for sites where frequent power outages are possible. 12.
CS725 Snow Water Equivalency Sensor absorption and energy degradation by the snow of the gamma rays from the ground is the basic information for the calculation of the SWE. Each time a gamma ray is detected by the CS725, it is placed in its corresponding bin in the energy histogram. This histogram is the basic data set for the calculation of the SWEs. Since it is statistical in nature, the accuracy of the SWE evaluation is proportional to the square root of the measurement time.
CS725 Snow Water Equivalency Sensor 14. Maintenance and Assembly There is no recommended user maintenance required for the CS725. CAUTION We do not recommend disassembling the CS725 for any reason. The CS725 instrument is very complex and is intended to be repaired or maintained only by factory trained personnel. It is recommended that the CS725 be calibrated every seven years. The reason for the timeline is to ensure the CS725 gamma ray detector does not drift out of specification.
CS725 Snow Water Equivalency Sensor FIGURE 14-2. CS725 inner tube shown FIGURE 14-3.
CS725 Snow Water Equivalency Sensor FIGURE 14-4. CS725 with top cap removed 15. Datalogger CRBasic Programming 15.1 Extended Data Output (.flla) Command The following program example reads the data values from the CS725 using the command [.flla]. This program obtains information in addition to reported SWE values such as radiation counts and other diagnostic information.
CS725 Snow Water Equivalency Sensor Alias Alias Alias Alias Alias CS725_Date_Time(1) CS725_Date_Time(2) CS725_Date_Time(3) CS725_Date_Time(4) CS725_Date_Time(5) = = = = = CS725_Day CS725_Month CS725_Year CS725_Hour CS725_Min Public CS725_StationID As String * 10 Public CS725_Values(17) As Float Alias Alias Alias Alias Alias Alias Alias Alias Alias Alias Alias Alias Alias Alias Alias Alias Alias CS725_Values(1) = CS725_SerialNum CS725_Values(2) = CS725_K_Uncorrected CS725_Values(3) = CS725_K_Counts CS7
CS725 Snow Water Equivalency Sensor 'Main Program BeginProg 'Prepare COM1 for the CS725 SerialOpen (Com1,9600,3,0,1000) 'Scan rate is dependent on application Scan (30,Sec,7,0) PanelTemp (PTemp,250) Battery (batt_volt) 'Based on the Factory default settings of the CS725 will 'calculate SWE on the Hour every 6 Hours. 'The CS725 is read every 6 hour in this program.
CS725 Snow Water Equivalency Sensor 'CS725_Crystal_TEMP_MAX *Suggest to Output to Final Storage* 'CS725_Hist_Blocks *Suggest to Output to Final Storage* 'CS725_K_Disp *Suggest to Output to Final Storage* 'CS725_Stats 'CS725_PWR_Volt *Suggest to Output to Final Storage* SplitStr (CS725_Values(loopcount),CS725SplitStr(loopcount + 3),"",1,0) Next 'Prepare the output time string from when the CS725 produced the data 'Format is YYYY-MM-DD HH:MM CS725_TIME_String = FormatFloat (CS725_Year,"%04.
CS725 Snow Water Equivalency Sensor 'Define Data Tables DataTable (Diagnostics,1,-1) DataInterval (0,1440,Min,10) Minimum (1,batt_volt,FP2,0,False) Maximum (1,batt_volt,FP2,0,False) Minimum (1,PTemp,FP2,0,False) Maximum (1,PTemp,FP2,0,False) EndTable 'Define Data Tables DataTable (CS725Hourly,1,-1) DataInterval (0,60,Min,10) Sample (8,CS725_RET_Values(1),IEEE4) EndTable 'Main Program BeginProg 'Prepare COM1 for the CS725 SerialOpen (Com1,9600,3,0,10000) 'Scan rate is dependent on application Scan (30,Sec,7
CS725 Snow Water Equivalency Sensor 38
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