Issue
How do I calculate the pulse constant for an MNL-800 BI object configured for pulse input?
The Pulse Constant is a user entered pulse scaling value used by the pulse algorithm for calculating the output based on a pulses per second frequency. The range of the Pulse Constant value is 0.1 to 1000.
Environment
MNL-800
Cause
How do I calculate the pulse constant for an MNL-800 BI object configured for pulse input?
Resolution
Calculating the pulse constant requires the value to first be scaled to the equivalent pulse rate in seconds. Two examples are shown below.
The first example represents a water meter that provides a pulse that represents cubic feet per minutes. The meter generates one pulse per minute that represents a rate of 10 cubic feet per minute. The pulse constant calculates on a per second basis so the first step is to determine what one pulse represents as a rate per second.
1 pulse per minute / 60 seconds = 0.0166666 rate per second
Next, divide this value into the desired output when this pulse rate occurs. In this case, the rate value is 10 so the pulse constant is equal to 10 / 0.01666666 or 600.
The second example represents an electric meter that provides a pulse that represents KW. The meter generates one pulse every 0.5 second that represents a rate of 15 KW. The meter will pulse twice every second (1 second / 0.5 second). The pulse constant is calculated by multiplying the rate value by 2 or a pulse constant of 30. A meter pulsing twice per second will generate an output of 30 KW.
Reference the WorkPlace Tech Tool Engineering Guide - Binary Input object (F-26580) for more details.