UDG1000 Hach PCX2200 Serial Port Input Driver configuration

Transcription

1 UDG1000 Hach PCX2200 Serial Port Input Driver configuration Introduction: The UDG1000 Hach PCX2200 Serial Port Input Driver is used to collect data from one or more daisy-chained Hach 2200 PCX Particle Counter (also known as Met One) via a serial port connection. Pre-requisites: 1. UDG1000 Software is installed on PC. 2. Hach 2200 PCX connected to Serial Port of PC or to USB port via Hach RS485 to RS232 converter (Hach Item Number # or for USB ) in accordance with the particle counter User Manual (Catalog Number ). 3. Make sure any analog devices are connected correctly to the particle counter(s). Make sure that the particle counter(s) are connected to the converter correctly. 4. Make sure the serial port is configured for the particle counter. The settings are: eight (8) data bits, no parity, one (1) stop bit, 9600 baud (see Hach 2200 PCX Particle Counter User Manual). Setup There are three (3) different timing variables to consider when setting up a parameter Sample Period, Count Period, and Polling Frequency. The Sample Period and Count Period are set up for the collector, while the Polling Frequency is set up for each parameter in the collector. Sample Period is how often (in seconds) we read the device. Count Period is how long (in seconds) we count particles.

2 Polling Frequency is how often the parameter is updated. For example: I want to know the number of particles counted in 15 seconds, and I need the latest value updated every minute. The Count period would be 15. I can set the polling frequency to 1 minute. The Sample period I set to 300 seconds (5 minute). Readings at 10:00 and every minute after that: Readings at 10:05 and every minute after that: If I m collecting values for particle size 1.0, I will get: Time Value 10: : : : : : : As you can see, my parameter will have the same value for 5 minutes, because my sample period is 5 minutes. A better setting might be to have the sample period less than the lowest polling frequency. If I really need my parameter updated minutely, then I might set the sample period to 30 seconds. I can also increase polling frequency, so if I only need to see values every 5 minutes, then I could set the sample period to 1 minute. Remember, sample period is for the collector and polling is for each parameter in the collector. NOTE: The auto-detect will not work if this plug-in is collecting data. Remember this is a serial port and can only support one connection at a time. If I set the sample period high enough, such as 60 seconds, I can auto-detect between readings. The sample period will lock the serial port as long as it needs to read from each device, so count period also plays a part here. For optimal use, you want the sample period as high as possible and the count period as low as possible and still get a valid reading.

3 1. Add a new collector. From the UDG1000 Main Menu go to Input>Collectors and click Add. 2. Select Hach PCX2200 Serial Port Plug-in from the list. Click Add. 3. Enter a name for the collector. Click Save. 4. Configure the collector. Option Serial Port Sample Period: Count Period: Description Select the PC s serial port (COM1, COM2, etc ) that the particle counter is connected to. Drop down displays available serial ports on the PC. This is the lapse time between taking samples to update the cache of values and should be greater than the count period. This is the time (in seconds) from when the particle counter starts counting particles and when it stops. 5. Click Save at the bottom of the Collector Configuration to save the settings and Probes. 6. From the UDG1000 Main Menu go to Input>Parameters 7. The Sensor Address is the particle counters address starting with 128 for device number zero (0). Sensor Address can be any value between 128 and 160 and correlates to the device number plus The Parameters for the listed sizes and analog units will be auto-detected from each particle counter. 9. Select the Tags to be tracked, click and the Parameters will be created.

4 Note: To select multiple parameters, use Shift-Click and Ctrl-Click UDG1000 will start to collect data for the parameters. To change a parameters polling rate, Decimal Places or Units click on the Parameter and click Edit NOTE: For analog signals, you must set up the minimum and maximum ranges or you will see NaN for values. When setting up an analog parameter, the engineering instrument units and the signal range limits will need to be set. Select the Source tab after clicking Edit button. In our example I have a turbidity meter that will produce readings between 0 and 10 NTU. The signal range of my device is a 4 20 ma signal. So I enter zero (0) for the minimum engineering instrument unit and 10 for the maximum. For the signal range I enter 4 for the minimum and 20 for the maximum.

5 Instruments and their lines have impedance variations and tolerance levels, so they can return different values than expected. These variations can be compensated for by adjusting the minimum and maximum signal range. The scale is linear following ohms law voltage = current X resistance. The resistance is 250 ohms for the particle counter. Slope for the turbidity meter will be engineering units over the signal range: 10 0 / 20 4 =.625. From there you can calculate what the minimum and maximum signal range will be based on the reading that UDG1000 returns compared to what the instrument is actually reading. The instrument used in testing had the following signal range settings:

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