pH ARC Sensors Modbus RTU Programmer’s Manual (EPHUM011)

2.6.2 PA9: Moving Average

The pH ARC Sensor provides new pH readings every 3 seconds. One has the possibility to smoothen the pH reading (PMC1) by means of a moving average applied to the 3-seconds-readings.

PA9 can be applied on 1 to 16 3-seconds-readings. The default value is 2.

Effect of Moving Average (n=1 vs n=16)

5.5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

mov av = 1

 

 

4.5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

mov av = 16

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

pH

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3.5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2.5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15:46

15:46

15:46

15:46

15:46

15:47

15:47

15:47

15:47

15:48

15:48

15:48

15:48

15:49

15:49

15:49

15:49

15:50

15:50

15:50

tim e

Effect of Moving Average (n=1 vs n=16)

5.2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5.18

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

mov av = 1

 

 

 

 

 

 

5.16

 

 

 

 

 

 

 

 

 

 

 

mov av = 16

 

 

 

 

 

pH

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5.14

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5.12

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5.1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15:46

15:46

15:46

15:46

15:46

15:47

15:47

15:47

15:47

15:48

15:48

15:48

15:48

15:49

15:49

15:49

15:49

15:50

15:50

15:50

tim e

Figure 2.6.2.1: Comparison of the response of a pH ARC Sensor to a change from pH 5.1 to pH 2.5, using no moving average (n=1) or a moving average over 16 3-seconds-readings.

Using moving average, the short term signal stability can be improved; on the other hand, the response time of the sensor increases with increasing moving average. A moving average over 16 samples results in a response time of at least 48 s.

Note:

PA9 is applied to both PMC1 and PMC6.

624300/01

page 27 / 67

Page 27
Image 27
Hamilton Electronics EPHUM011 manual 2 PA9 Moving Average, Effect of Moving Average n=1 vs n=16