Cmdtwain how to scan multiple pages into one pdf file?

Question

cmd/bat

Now in the registry, the scan button in the printer is running a batch file:

set dir1=C:\TEST\ScanTo\
set strTime=_%Date%_%Time%
set strTime=%strTime::=-%
set strTime=%strTime:,=-%
set strTime=%strTime:/=-%
%SYSTEMDRIVE%
cd\
cd "Program Files"
cd CmdTwain
 
CmdTwain.exe /PAPER=A4 /RGB /DPI=300 /JPG75 "%dir1%\Scan_%strTime%.jpg"
::"%dir1%\Scan_%strTime%.jpg"
exit

I want to implement a version with pdf. But it is necessary that there is a choice on the printer whether to continue scanning into one file.
Here I don't know how