Xylem XL Series H-522 - Plus - Manual (Page 114)

13-4 Counter And Frequency Inputs
XL™ Series
Cnt & Txd Both counters are enabled, and if the ALERT radio option is enabled, the system
checks to see if an ALERT transmission should be sent.
Cnt & Log This mode could be called “Count, Scan and Log”. The counters are enabled, and
the XL™ will execute a scan at the time of each event (count). All sensor inputs
defined in the logging report options will be serviced and logged to the data file at
the time of the event. Options such as log rates and column functions are ignored
for this log entry. The Tscans variable is not incremented by this scan.
Cnt & BAS1 In this mode a pulse on the counter input will cause the counters to increment and
will also execute the BASIC1 program if loaded.
PC Interface View Built In Display Screen
W - Rate Win Size: 15 Rate Win Size [15 ]
There is a variable called CtRate. This variable is the rate at which the counter is activated
during the rate window. The range of the rate window size is 1 to 1440 minutes which is one
minute to one day. The count rate is calculated by taking the total rain for the time period and
dividing it by that time in minutes. Now the rate of rain fall is not based on a set starting time
like midnight or the top of each hour, but starts at the current scan and goes back in time to the
start of the window, or in other words this is a sliding window.
An example of using this option and the CtRate variable follows. The user wants to record rain
fall and the rate of rain fall. The logger is set to log date, time, totcnt for rain fall, and CtRate for
the rate of rain fall. The scanning is set to 15 minutes and the rate window size is set to 1440 for
a one day rate window. Now as the data logger scans and logs data it will log the rain fall in the
third column and the rate of rain fall in the forth column. If in a 24 hour time period it rains only
0.01 inch (one tip) it would report 0.000006944 which is 0.01 divided by 1440, or 0.000006944
inches of rain per day. If it rained for half a day at .5 inches and then 0.25 inches for half a day,
at the end of the 24 hour period it would report 0.375 inches of rain for that 24 hour period.
PC Interface View Built In Display Screen
D - Debounce Time: 250 mS Ctr Debounce [250] mS
This option sets the debounce time in milliseconds. The range is 0 to 255 milliseconds. The
debounce time is the duration of time after a count is received before another count will be
recognized. Most electrical switches have a characteristic known as bounce so when the switch
is turned on or off it will fluctuate between the on and off condition for a some time period,
normally milliseconds, and then stabilize to the desired position. These fluctuations can cause
added unwanted counts.