Assessments - 3, GPA: 4.3
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Facilidade de uso
Programming In the CR510, CR10X, and CR23X datalogger, Instruction P1 or P2 can be used. Example 1 uses a single-ended measurement for the CS512 probe; example 2 uses a differential measurement. The example measurement instructions that follow do not store data to final storage. Additional instructions (typically P92, P77, and output processing instructions such as P70) are required to store data permanently. EXAMPLE 1. Sample Program using P1 1: Volt (SE) (P1) 1: 1 Reps 2: 24 250 mV 60 Hz Rejection Range ; code 23 used for CR23X 3: 1 SE Channel 4: 1 Loc [ DOmV ] 5: 1.0 Multiplier *See Calibration* 6: 0.0 Offset EXAMPLE 2. Sample Program using P2 1: Volt (Diff) (P2) 1: 1 Reps 2: 24 250 mV 60 Hz Rejection Range ; code 23 used for CR23X 3: 1 DIFF Channel 4: 1 Loc [ DOmV ] 5: 1.0 Multiplier *See Calibration* 6: 0.0 Offset In the CR1000, CR800, CR850, and CR3000 dataloggers, instruction VoltDiff or VoltSE is used to measure the CS512 probe. EXAMPLE 3. Sample Program using VoltSE VoltSE (DOmV,1,mV250,1,1,0,_60Hz,1.0,0) EXAMPLE 4. Sample Program using VoltDiff VoltDiff (DOmV,1,mV250,1,True ,0,_60Hz,1.0,0) In the CR200 series dataloggers, only the instruction VoltSE is used to measure the CS512 probe. EXAMPLE 5. Sample Program using VoltSE. VoltSE (DOmV,1,1,1.0,0) Campbell Scientific CS512 Oxyguard Type III Dissolved Oxygen Probe 8. Calibration The multiplier is used to calibrate the CS512 probe. To calculate the multiplier: 1) Program the datalogger using a multiplier of one. 2) Place the OxyGuard probe in the air, shaded from the sun. Wait for readings to stabilize. This may take 15 minutes or more. 3) Determine the air temperature and barometric pressure. 4) Using a calibration chart such as that provided in the probe’s manual, determine the oxygen concentration of the air. 5) Use the following equation to calculate the multiplier: M = P/R M = Multiplier P = Concentration in PPM of the air (from the calibration chart in Appendix A) R = The signal output of the OxyGuard probe when using a multiplier of one 6) Change the multiplier in the datalogger program from one to the calculated number. A more common way to enter the multiplier is to insert a separate instruction in the program. This will allow a new multiplier to be added to the program without rewriting, compiling, and downloading the program to the data logger. In the CR510, CR10X, and CR23X, use Instruction P36. The multiplier is entered into an input location called DOmult using the numeric display in PC200W, PC208W, LoggerNet, PC400, PConnect, PConnectCE, or the CR10KD. EXAMPLE 6. Sample Program using P36 57: Z=X*Y (P36) 1: 1 X Loc [ DOmV ] 2: 2 Y Loc [ DOmult ] 3: 3 Z Loc [ DOppm ] In all dataloggers that use CRBasic, an expression is written. The multiplier value is entered into the expression through the Public Table using the numeric display in PC200W, LoggerNet, PC400, PConnect, and PConnectCE. EXAMPLE 7. Sample Program using Expression DOppm = DOMult * DOmV Campbell Scientific CS512 Oxyguard Type III Dissolved Oxygen Probe 9. Maintenance The CS512 probe needs little maintenance. Regular cleaning of the membrane is all that is required. The membrane is very durable and can be cleaned with a cloth or soft paper. Do not scratch it clean with your fingernail. 10. Agitator Control In low flow conditions (less than about 5 cm/sec), it may be necessary to add an agitator to the CS512 probe. Campbell Scientific ships the agitator with a repeat cycle timer. Using the repeat cycle timer requires no datalogger programming. However, some users choose to use a solid state relay and have the datalogger agitate the water on the probe face either periodically throughout the day or just before measurement. Agitating just before the measurement saves on power and causes less wear and tear on the agitator and probe membrane. The wiring for the agitator as controlled by this example program would be as follows: WHITE BLACK Agitator + - 4 1 #7321 Relay Crydom D1D07 3 2 Ground/G Datalogger Port C1 12 V Battery FIGURE 10-1. Agitator Wiring The following instructions would trigger the agitator as discussed in the agitator manual. In the CR510, CR10X, and CR23X, use instruction P86 and P22. Campbell Scientific CS512 Oxyguard Type III Dissolved Oxygen Probe EXAMPLE 8. Sample Program using P86 and P22 Instructions 45: Do (P86) 1: 41 Set Port 1 High 46: Excitation with Delay (P22) 1: 1 Ex Channel 2: 20 Delay W/Ex (units = 0.01 sec) 3: 0 Delay After Ex (units = 0.01 sec) 4: 0 mV Excitation 47: Do (P86) 1: 51 Set Port 1 Low 48: End (P95) In the CR200 series dataloggers, use the Portset instruction. EXAMPLE 9. Sample Program using Portset Portset (1,1) Delay(500,msec) Portset(1,0) In the CR1000, CR800, CR850, and CR3000 dataloggers, use the Portset instruction. EXAMPLE 10. Sample Program using Portset Portset (1,1) Delay (1,500,msec) Portset (1,0) The above example is not as power efficient as possible and would require AC power to maintain a sufficient battery charge. If it i...