How To: Log Data from Pulse Meters

Configure a register to convert pulse signals to more meaningful information

Overview

This article describes using pulse sensors to read from energy meters, but any meter such as flow meters may be used. The only difference is to change the formula register from "Power [W]" to the particular measurement and using a "constant" that represents 1 unit (per pulse) of that measured item, for example cubic meters if volumetric flow. If the eGauge does not support the measured item, "number with 3 decimals" may be used instead.

Prerequisites

This is an advanced configuration topic. If you're not familiar with basic eGauge configuration, read over the basic configuration steps found in the Getting Started section.

Required hardware:

EG4xxx meter
Installed Sensor Hub and EPS sensor

Instructions

Step 1: Using CTid, configure the sensor input and create a register for the pulse count, where "S1" is the sensor input the EPS is connected:

Step 2: Create a power formula register to calculate the power reading from the pulse count. The formula register contents should be: $"Pulse Register" * constant * 3600 where Pulse Register is the register name of the register recording the pulse count, and constant is the meter Wh constant factor (effectively, in watt-hours what one pulse indicates or "Wh-per-pulse"). The below screenshot shows the calculation for a single pulse representing 5.3 watt-hours:

Math behind the formula register

The reason 3,600 is multiplied by the Wh-per-pulse is due to the meter reading data at second-granularity and there being 3,600 seconds in one hour. For example, if there is a meter constant of "1" (meaning 1 pulse is 1 Wh), when the eGauge meter receives 1 pulse, it will record "1" at that second in time, which will show as 1 watt during that 1 second it was detected (1 watt-second of energy). To convert watt-seconds to watt-hours, we multiply by 3,600 seconds.

If a single pulse represents kWh rather than Wh, the formula will need to be multiplied by 1,000, such as:

$"Pulse Register" * constant * 3600 * 1000

Notes:

Pulse meters change output state each pulse; that is, the output goes from open to closed to indicate a single pulse, than open to closed to indicate the next pulse, and alternates continously for each pulse. If testing the pulse sensor and recorded data by shorting the SIG and GROUND terminals, contacting will result in 1 pulse, and releasing will result in an additional pulse.