Fisher 244EH, 244ER manual Intermittent Sensor Algorithm and Damping

Intermittent Sensor Algorithm and Damping

Step Changes Greater than Threshold Value

Input
Output without Algorithm	Total of All Step Changes

Output with Algorithm (Default)

0500 1000 1500 2000 2500 3000 3500 4000

Time (in 500 ms increments)

D)If an open sensor is validated at the end of the first update cycle (Time = 500 ms), the output will go directly to alarm level. The original spike (at Time = 0 ms) will not be seen at the output.

Open Sensor
Input
	False Output
Output without Algorithm	Alarm

Output with Algorithm (Default)

0500 1000 1500 2000 2500 3000 3500 4000 Time (in 500 ms increments)

Case 3: Temperature Change Within the

Threshold Value (2 % of Range)

If the transmitter detects an input change that is within the threshold value, it reports the new value within one output cycle (500 ms).

If the transmitter has both intermittent sensor detect and damping enabled, the output reading is calculated by the following formula:

Damped Value = (P N) × ⎛ 2T – U⎞ + N

– ⎝-----------------⎠

2T + U

P = previous damped value

N = new sensor value

T = damping time constant

U = update rate

The transmitter outputs the corresponding value on the damping curve within 1.75 to 2.0 seconds and updates the output reading every 500 ms thereafter, according to the damping equation above. At the value to which the damping time constant is set, the transmitter output is at 63% of the input change.

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