Artisan version 3.1.2 allows connecting energy meters to log
precise measurements of energy consumption.
Artisan can connect to one or two meters simultaneously allowing
measurement of gas energy consumption and/or electricity energy
consumption. This allows the roasting
operation to accurately monitor and report on its energy use and carbon
footprint.
In 2021 Artisan version 2.4.6 introduced the ability to estimate energy consumption and CO2 production of the roasting process. Using this set of features, roasting operations are able to monitor their carbon footprint, monitor operational and energy efficiency and report on the results. With this objective data improvements in the process can be measured, evaluated and reported.
Please see this blog article that describes in depth how the Energy Calculator works. This article will provide the detail for how to configure and collect information from an energy meter to include in the Energy Calculator.
Some basics about energy meters
Energy is the ability to do work or heat an object; power is the rate at which energy is moved, or used. Power is measured instantaneously. Electricity power is commonly measured in kilo-watts (kW). Electricity energy is measured over time and is commonly expressed in kilo-watt hours (kWh). For example, if an electric heating element consumes 5 kW continuously for one hour, the energy consumed is 5 kWh. An energy meter measures the amount of power passing through it and accumulates (adds it up) over time to provide a measurement of energy. That means the reading will always be increasing when the energy is flowing in one direction. Depending on the amount of power being used, the energy reading may increase quickly or slowly.
There are a variety of energy meters available. Some roasting machines that use electricity as the energy source for heating may have an electricity energy meter built in to their PLC. If not built in, an energy meter that is external to the roaster can be used to measure the roaster’s consumption. These external meters are sometimes referred to as sub-meters because they are not intended to measure the consumption of an entire building. Sub-meters can be used to measure the consumption of a single device, like a coffee roaster. To be useful, an electricity sub-meter must be chosen that has a resolution appropriate for a single roast. Gas sub-meters designed with a scale to measure the consumption of just a single roast are less common though they are available. They are often called flow meters and report flow rate or total volume over time that can easily be converted to energy consumption.
One key feature required is the ability to read the energy meter digitally. Without it there is no way for Artisan to get the meter’s data. The most common interface is MODBUS SERIAL RTU over RS-485. There are other interfaces that can be accessed by Artisan. This article will focus on MODBUS and Yocto interfaces.
Overview - Connecting a meter to Artisan
Intake of meter data is done using an Extra Device (Config>> Device>> Extra Devices tab). This Extra Device is then chosen as the Meter Source in the Energy Loads tab (Roast>> Properties>> Energy tab>> Loads sub-tab). It is important that the Extra Device is scaled to match one of the available meter Units found on the Energy Loads sub-tab. The type of energy being measured by the meter should be chosen from the Type pull down. The meter can be given a descriptive Label. That’s all there is to do. Below we’ll go into a few examples.
Example 1 - Connecting a MODBUS Electricity Meter
Electricity energy meters are available in single and 3 phase models. For this example, we are using a meter with a MODBUS SERIAL RTU connection over RS-485. Using a RS-485 to USB adapter we are able to connect to a single serial port to exchange information with the meter. For more information on connecting RS-485 devices see this blog post.
It is important to have the MODBUS register map for your meter available to identify the register holding the accumulated (or total) energy value. Our meter uses the register at address hex 0100 (decimal 256), and the energy is stored as a floating-point number with resolution down to 1 Watt. Note that there is no standard location or data format for all meters so you must have the meter’s documentation to be successful.
First, create the Extra Device to hold our energy data (Config>> Device>> Extra Devices tab). Our meter will be on MODBUS Input 1 so we use the “MODBUS” device, which is the device for inputs 1 and 2.
We gave the device a label “EnergyMeter”. Though not required, we unticked all the display options. If you want to show the energy curve leave Curve 1 ticked.
The serial port must be set properly for your system. Ours is COM5 and our meter is at 9600 baud. Your settings may be different.
Using the information above we set the MODBUS Input such that the Slave number is 3, the Register is 256 and the Decode is Float32.
Click OK and open Roast>> Properties>> Energy tab>> Loads sub-tab. Here we set a Label for the meter. The Unit chosen is kWh. This matches the unit for the data read from the meter and stored in the Extra Device. The type is set to “Elec” and finally we choose the Source to be the Extra Device with label “EnergyMeter”.
The Electric Energy Mix spin box allows for reducing the CO2 calculated based upon the percentage of renewable energy used to create the electricity. At 100% renewable the CO2 calculated to produce that electricity will be zero. Note that the CO2 calculations regard only the energy consumed and do not attempt to calculate the CO2 generated by the coffee seeds.
Example 2 - Connecting the Yocto-Watt
The Yocto-Watt is a single phase watt meter produced by Yoctopuce. Artisan already supports this device so connecting it is quite straightforward.
Create the Extra Device to hold our energy data (Config>> Device>> Extra Devices tab). Use the device
“EnergyMeter”. The Yocto-Watt returns energy data in watt-hours (Wh). Artisan’s energy calculator uses the unit kWh so we must scale the data. There are two ways to do this. One is to use an equation to perform the scaling before the value is stored to the extra device. The second is to store the raw data and create a Virtual Device that stores the scaled data. This example shows the first approach. Don’t worry, the scaling does not truncate the stored data. No precision is lost.
Click OK and open Roast>> Properties>> Energy tab>> Loads sub-tab. Here we set a Label for the meter. The Unit chosen is kWh. This matches the scaled unit calculated from the data read from the meter and stored in the Extra Device. The type is set to “Elec” and finally we choose the Source to be the Extra Device with label “EnergyMeter”.
The Electric Energy Mix spin box allows for reducing the CO2 calculated based upon the percentage of renewable energy used to create the electricity. At 100% renewable the CO2 calculated to produce that electricity will be zero. Note that the CO2 calculations regard only the energy consumed and do not attempt to calculate the CO2 generated by the coffee seeds.
Example 3 - Connecting a Gas Meter
This example uses a Coriolis mass flow meter capable of totaling and reporting the volume of gas measured in liters(l) with resolution to milliliters (ml). This resolution allows measuring the gas consumed by a single roast. The volume of gas must be converted to energy in the symbolic equation of the special device. This example assumes the gas is LPG.
This example follows closely with the steps outlined above in “Example - Connecting a MODBUS
Electricity Meter.” Please refer to that example and the configurations shown below.
Create an Extra Device to read the meter. Here we use a symbolic equation to convert the volume in ml to energy in kWh. The conversion value depends on the caloric content of the gas. Our gas contains 7.11 kWh per liter at 15°C. We did not adjust for actual temperature. You may do so if you want even greater precision.
Using the information from the meter documentation set the MODBUS Input such that the Slave number is 4, the Register is 0xE808 (decimal 5940) and the Decode is Float32.
Open the Roast>> Properties>> Energy tab>> Loads sub-tab. Set the Meter Label, Unit and Type and Source.
Summary
In these examples we've shown how to connect a variety of energy meters, both electric and gas, to Artisan to read and record roast batch consumption data. With this data roasting operations can monitor, report and improve their energy consumption and CO2 emissions.
Dave and Marko
