6 Fine-Tuning Using Your Log Files

6.1 Copying Your Log Files to Your Mac

You must first create and copy FreeAPS-ng log files from your iPhone to your Mac computer.

  • Tap Share logs at the bottom of Settings in FAX-ng

This will create two log files, log.txt and log_prev.txt, and open a screen allowing you to transfer them by a variety of methods.

  • Save these files on your Mac in a Folder of your choice
  • Leave the Folder window open on your Desktop

6.2 Setting UAMSMB/SMB Limitations

6.2.1 Safety Limiters

The following Settings act as “safety limiters”:

Max UAMSMB Basal Minutes
Max SMB Basal Minutes
Autosens Max
Autosens Min

They do they not affect calculations except by putting up fences.

The primary focus on a new setup is to have initial Settings* so that the system is immediately able to function adequately using its default calculations.

But if your Basal Minutes is set to 30 and your Basal Rate is .1, and the app wants to give you an SMB of 2U, the Basal Minutes setting will limit it to .5U at a time, and your blood sugar will be high forever.

So you will want to increase Basal Minutes to a value that allows the algorithm to do its job. The ideal is to create Settings that allow 95% of any UAMSMB/SMB calculation made by FAX-ng to influence insulin delivery. For this we need to ensure that:

SMB is not limited by maxUAMSMBBasalMinutes
SMB is not limited by maxSMBBasalMinutes
Dynamic ISF limited by autosens_max setting: 1.3 (1.3)

To understand SMB and its limitations factors, you can read:
Understanding Super Micro Bolus (SMB) in the OpenAPS documentation.

6.2.2 Open Terminal on Your Mac

The Terminal application is in Applications > Utilities > Terminal

6.2.2.1 SHORTCUT to open Terminal

  • Click on the Desktop in Finder
  • Hold the [COMMAND] key then tap the [SPACEBAR]
  • Start typing terminal when the Spotlight Search bar opens
  • Press [RETURN/ENTER] to open the Terminal application

6.2.2.2 Change focus to the Log File Directory

  • Type cd [SPACE] in Terminal
  • Switch to Finder
  • Drag the small Folder icon where you saved the log files, into the Terminal window
    • path/to/the/log/files/folder will appear next to cd
  • Press [ENTER/RETURN]. This will change Terminal to the log file directory.

You can type ls then tap [RETURN/ENTER] to list the log files.
The following commands will now work correctly.

6.2.3 Find and Compare The Ratio of SMB-Limited Lines

First, find find the total number of lines from the log pertinent to each.

Copy and paste the first line of each command (below), after the $ prompt. The first line is the command, the second the returned result:

grep maxUAMSMBBasalMinutes log.txt | grep limited | wc -l
     114

Then find the number of lines that are SMB-limited:

grep maxUAMSMBBasalMinutes log.txt | grep "SMB limited" | wc -l
      57

Compare the two results. If the number of limited lines is more than 5% (in the above examples it obviously is), you need to adjust maxUAMSMBBasalMinutes, guided by these log reports.

Sort the result by calculated units (the last value on the line):

grep maxUAMSMBBasalMinutes log.txt | grep "SMB limited"  | sort -n +20

Scroll through the search results to see how much the algorithm is limiting insulin delivery. The overall idea is to “ignore” the extreme SMBs.

In the log file, you will see lines similar to:

DEV: JavaScript log: SMB is not limited by MaxUAMSMBBasalMinutes. ( insulinReq: 0.53U )
DEV: JavaScript log: SMB limited by maxUAMSMBBasalMinutes [ 60m ]: 1.5U ( 6.28U )

There will be entries for both maxUAMSMBBasalMinutes and maxSMBBasalMinutes

Optimally, you want to have more “not limited” lines then limited, with limited lines being less then 5% of all of the lines. If they are less than 5% of all lines, you don’t need to change your settings.

To adjust maxUAMSMBBasalMinutes to reduce the percentage of lines that are limited, look for the line that represents about the mid-way of limited values. For example, if you have something like:

DEV: JavaScript log: SMB limited by maxUAMSMBBasalMinutes [ 60m ]: 1.5U ( 6.28U )
DEV: JavaScript log: SMB limited by maxUAMSMBBasalMinutes [ 60m ]: 1.5U ( 5.72U )
DEV: JavaScript log: SMB limited by maxUAMSMBBasalMinutes [ 60m ]: 1.5U ( 6.1U )

Use the entry with 6.1U as your adjustment point, with the formula:

   60m * ( 6.1 / 1.5 ) = 240

And use the rounded results for your new value in maxUAMSMBBasalMinutes. Do the maths and up your UAMSMB basal minutes by that amount. For example: the algorithm bolused 1U insulin when it says it really wanted to bolus 3U, so increase UAMBasalMinutes by 3x in Settings.

If you need to adjust, there are going to be more lines then the above to work with, but the value in parenthesis is what the system has calculated you require in the way of insulin, and the value outside is the limit BASED ON BasalMinutes. The 1.5U will vary depending on time of day, as its determined by your Basal Rate at the time of calculation.

When you make the change, give it 24 hours before checking and adjusting again.

6.2.4 An Easier Way for the Rest of Us

Heres a much easier way for non-technical people: * Email log files to yourself * Open log_prev.txt * Press [CONTROL/COMMAND] + F to perform a search * Enter e.g. SMB is limited by maxUAMSMBBasalMinutes into the Search field. * Press [RETURN/ENTER]

Search for either is limited or is not limited to get the numbers for both. If the [limited]/[is not limited] x 100 is less than 5 (5%), then dont change anything.

6.2.5 Checking The Results

To check this (except the first day or so), run the above commands on the log_prev.txt file, which reports the previous 24-hour period. Leave it run for a full day before rechecking.

If everything else is set up correctly for you, these SMB maximums wont be needed in the future. But now you can know for sure that they are based on the results returned in your log files.