Recent roast profile analysis has focused on using Development Time Ratio (DTR), rather than time, as being the appropriate measure for making changes in power or air flow after first crack begins. Artisan allows multiple excellent methods to display DTR, and many other useful metrics too. This post will discuss how DTR can be displayed in Artisan during and after roast logging.
Development time ratio is defined as the ratio, expressed as a percentage, of time since first crack started divided by the total time since the roast began by charging the beans. DTR can be challenging to calculate in your head, especially during a roast when there are other distractions!
Consider this example to see how DTR is calculated. Assume first crack start (FCs) happens at exactly 9 minutes after the roast began (CHARGE). It is easier to do the math using seconds so we convert 9 minutes = 9*60 = 540 seconds. Next assume the time of interest is at 50 seconds after FCs. What is the DTR at this time? Take the time after FCs, which is 50 seconds, and divide by the total time since CHARGE. The total time is 540 seconds (9 minutes) plus 50 seconds. We calculate 50/(540+50) = 50/590 = 0.085. Since DTR is normally expressed as a percentage the DTR is 8.5%.
Fortunately you do not have to do this math in your head. Artisan will do it for you. During the roast Artisan will display the real time DTR. After the roast Artisan has a few ways to inform you of the DTR at any given time.
Note: DTR has no meaning and is not a valid measurement before FCs.
Development Time Ratio During Roasting
The most common way to display DTR while logging with Artisan is to use the Phases LCDs. From the menu go to Config >> Phases.
The easiest way to display the real time DTR is to tick the box under Phases LCDs All. Be sure Phases LCDs is also ticked.
Note: Leaving Phases LCDs All unticked and selecting Percentage for the Finishing phase will also display DTR in the LCDs. For more information on the options available for the Phases LCDs see the Artisan Quick Start Guide.
This is how the LCDs will look while logging a roast after FCs. Note that DTR% is labeled Dev% here. Also, remember that the Dev% LCD shows only after FCs has been recorded, so do not be surprised at the beginning of the roast when you cannot see the Dev% LCD.
Plotting Development Time Ratio as a Curve in the Graph
To plot DTR as a curve on the graph we need to use a virtual extra device. If you are already using extra deices add one more as explained below. If you do not use extra devices, this is a good time to learn how.
Open the Extra Devices configuration by using the menu Config>> Device... and selecting the Extra Devices tab.
1. Click Add to add a new extra device. Be sure the Device Type is set to Virtual.
2. Choose a color for the DTR curve, Color1, or leave it in the default black.
3. Change Label1 to "DTR".
4. Next, copy the following equation and paste it into the field y1(x).
100 * max(0, (t-t{FCs})) / (t-t{CHARGE})
Note: The y1(x) field was expanded by dragging the vertical line between the y1(x) and y2(x) titles with the cursor as shown in the image above.
Note: Read more about virtual devices and the related settings in Symbolic Formulas: Basics, New Variables and Applications.
5. Drag the scroll bar below the table to the right to see the additional fields.
6. Optionally, uncheck LCD1. If you use the Phases LCDs as described above there is no need for this additional LCD. It is redundant. However, if you do not use the Phases LCDs All mode leave LCD1 checked so it will be shown during recording.
7. Be sure Curve1 remains checked. 8. Uncheck LCD2 and Curve2. At the moment these are unused so we do not want them displayed.
9. Check Δ Axis1. The plots the DTR curve using the axis on the right side of the graph.
10. Click OK. The Ports Configuration windows will open. Presumably you already made this configuration so click OK to continue.
Here is a look at a completed roast showing the DTR curve.
Notice DTR begins to rise at FCs, which is marked at 8:34. DTR is not a straight line. There is a slight curve to it. The DTR value is read using the Y axis values on the right hand side of the curve.
Reading the DTR Graph
One can easily see the DTR value at any point in time on the graph. A fast way to precisely read the DTR is to use the mouse pointer.
At the top, near the center of the Artisan window, are shown the x and y coordinates of the mouse pointer. This allows you to read the time and temperature at any point in the profile. The y axis value normally shows the temperature using the left hand axis but can this be easily switched to read the right hand axis by pressing the 'd' key on the keyboard. Here we see that the mouse pointer is showing the roast time is 9:25 (x=9:25) and the DTR is 8.7% (y=8.7).
Note: For more on keyboard shortcuts use the menu Help>> Keyboard Shortcuts or visit the Quick Start Guide.
Another powerful tool when analyzing graphs is the Mouse Cross. Turn this on by hitting the keyboard key 't' (on Windows you may have to tap twice or better yet use Ctrl+SHIFT+t). The mouse cross adds cursor lines to better position the mouse pointer. Added to the view below is the Gas setting. The mouse cross is lined up on the last Gas change We see that the change was made at 9:43 when the DTR was 11.9%.
Note: The mouse cross is a powerful tool. Try click and drag. Additional metrics useful for other types of analysis will be shown in the message area. A future post will go into detail on ways to use the mouse cross.
What About Profiles Recorded Without the DTR Curve?
Artisan has you covered! Open your previously recorded profile. Follow steps 1-9 above. At this point click the Update Profile button. The DTR curve will calculated and drawn into your profile.
CAUTION: Your profile data will be changed when you click Update Profile! Only the virtual device data will be altered. If there is any difference in how the virtual devices are defined in the configuration page compared to your recorded profile, the virtual device data in the profile will be overwritten with new data. It is recommended to save the updated profile to a new file name thus preserving the data in the original file.
Showing Development Time Ratio on Special Events After the Roast
If you are using Artisan v2.4 or later the special event annotations can be used to display the DTR right on the Gas change line in the graph.
Showing the DTR at changes in special events, such as Gas or Air, greatly helps in post roast analysis. Detailed information on how to show DTR in this manner can be found in the blog post Special Event Annotations.
Note: It is not necessary to setup a DTR extra device to display the DTR in special events annotations. The special events annotation will work with any profile.
Total DTR of Any Roast Profile
The value for a roast's total DTR is included in the Roast Report and the Ranking Report, found under the menu File>> Report.
Total DTR can also be shown in the graph using the Statistics Bar.
The Statistics Bar is turned on by default In Artisan. It can be turned on or off and data to be displayed choices made in the Statistics configuration window, from the menu Config>> Statistics. Tick Time to show the time and percentage values for the phases and tick Bar to add a visual bar display of the phases.
Note: It is not necessary to setup a DTR extra device to display the total DTR in the Statistics Bar or in reports. It is necessary that the events CHARGE, FCs, and DROP be marked in the profile. Without them the total DTR cannot be calculated.
With these many methods of displaying DTR Artisan can help you better control your roasts and deepen your ability to perform post roast analysis. Enjoy working with Artisan!
Dave
