ACAD_db is designed to sync AutoCAD attribute values from database when drawing is opened and when the command "AcDbIn" is used. In this case if attribute has sync dir "DWGtoDB", then attribute value will not be synced from database and instead shows message to user "Has DB->DWG Sync restriction".
ACAD_db is designed to sync database from AutoCAD attribute values when document is saved [Only edited or newly inserted blocks with attribute] or when command "AcDbOut" [All blocks with attribute] is used. In this case if attribute has sync dir "DBtoDWG" then attribute value will be not be synced from database and instead shows message to user "Has DWG->DB Sync restriction".
"When drawing is opened ACAD_db checks whether it is compatible by checking whether drawing full name is listed in the table "JTBW_Files". If drawing is compatible and not read only it attaches events to the drawing. Hence all commands and events will start to work.
"Drawing becomes compatible to database from the time the command "AcDbMake" is used. If any blocks with attribute were inserted before using the command "AcDbMake", those blocks will not be added to edit block collection. Only blocks edited or newly inserted after making drawing compatible are added to edit block collection. Hence preferably, user needs to make drawing compatible and insert the blocks. If user has some blocks inserted before making drawing compatible, then user needs to use command "AcDbOut" as it syncs all blocks.
But if drawing is newly created or not listed in the drawing, then user needs to use command "AcDbMake" to make it compatible. If there are any existing blocks in the drawing before making the drawing compatible, it is advised user to use command "AcDbOut" to sync all pre-existing blocks.
If a drawing is opened and you make a change in the database this change will be lost when you save the drawing unless the SyncDir is DBtoDWG. Make sure to change in the database only if the drawing is closed or if you directly after the change run AcDbIn.
If DWGtoDB is used as SyncDir on an attribute the database will not be updated if just the drawing is opened. You need to either make a change on the block attributes and save or run the "AcDbOut" command to have it updated.
If you make a change in a drawing that is ACAD_db compatible but not having the program loaded the changes might not be reflected to the database. Say you take a copy of a block that can be synchronized and make some changes to the attribute values. Now if you load the program and open the drawing and make some other changes and close and save the drawing the new block with its attributes will not be added to the database. To force an update you would need to run "AcDbOut".
The program does not write values from the database to the drawing if the attribute contains a field. In this case the sync is only done from the drawing to the database.
The command line history in AutoCAD is as default 400 rows and sometimes the status returned by ACAD_db can contain many more lines. One way is to increase this to 2048 rows using this method described here: http://www.jtbworld.com/lisp/historylines.htm
LOGFILEON, LOGFILENAME, LOGFILEMODE and LOGFILEPATH can in AutoCAD be used if you want to direct the command line history to a file so you can investigate the information that comes on the command line.