For the turret 5442-ZE (2.7 - 12mm lens) the focus maximum steps is 2275. To find this number, the simplest way is to change the zoom speed from 20 to 1. Then move the tab to the right as far as it will go. That mouse over number will be the max steps for the camera zoom.
The other way is to use the Dahua API and extract the data for each camera of interest.
Code:
http://admin:password@192.168.55.50/cgi-bin/devVideoInput.cgi?action=getFocusStatus
status.Focus=0.610922
status.FocusMotorSteps=2930
status.LenAdjustStatus=0
status.Status=Normal
status.Zoom=0.285275
status.ZoomMotorSteps=2275
From the API data to determine the tab number Zoom x Zoom Motor Steps. Or 2275 x .285275 = 649.
Placing these number in the above calculator the set point for the desired lens focal length is as follows:
2.8mm - 24.5
3.6mm - 220.2
6.0mm - 807.3
10mm - 1785.8
Note that a 6mm lens on different sizes of sensors will produce different FOVs.