How does the 2 sigma test routine function on the HI 2160RC?

The 2 Sigma Test feature is only in the HI 2160RCplus and is used to measure the performance of the feeder system, and can be run on demand during all feed cycles. The test measures the decreasing weight on a scale by sampling a user selected number of samples over a user selected time period. The HI 2160RC+ stores the amount of weight that left the scale for each time interval and then time and date stamps the sample. The mean value of the total selected readings is calculated. The standard deviation is calculated and multiplied by two (2) then divided by the mean value to determine the 2 Sigma accuracy of the feeder system under test. If the feed cycle is interrupted in any way (system malfunction, operator pause, REC mode or refill mode) an invalid test alarm is displayed and the test is aborted. Once the test is complete the results are kept in the 2 Sigma Data memory and can be displayed by selecting the 2 Sigma Data sub-menu in the Test Menu. Complete test information can be gathered by having a communications collection device or printer attached to the serial port.

The 2 Sigma accuracy test of a feeder is the repeatability of the feed rate expressed as a percentage of the Mean feed rate. You can perform the 2 Sigma Test at any time when in Continuous mode. When in Batch mode it is recommended that you choose the parameters so that the test can be completed by the end of the batch process, otherwise you will not get valid test data. It is recommended that the parameters be enabled when there will not be any interruptions or refills occur during the test.