VS 2008 Getting Number Of Row From A Grid In Another Program

I have a datalogger with his own program on Windows via a RS232 port. This datalogger records data in two ways :

1- continuously (see picture 1)
2- when pressing 'Start recording' button.

The datalogger record a value each 1 sec. Between 2 values, I need to move a stepper motor. I want to synchronize the stepper motor with the datalogger. So, right after the data is recorded, I move the motor and I wait for the second data to be recorded, etc. The problem is the synchronisation. I have access to 2 triggering method when the data is recorded :

1-when a row is added in the grid (picture 1)
2-when the 'Recording' value change (from 5 to 6 by example)(picture 2)

The easiest option would be the second one because the 'Recording' value isn't a textbox, it's included in the general form. I cannot access to it directly. The class of the datagrid is Thundergrid and his name (Caption) is LIST. I want a VB program that will do the following..When I press a button in My Form :

-Get the handle of Thundergrid class, LIST named.
-Wait until the datagrid row number is 10.
-Then, a variable n will count +1 at each added row in the datagrid.
-Each time the n value will change (datagrid add a row), the motor will move.
-When the n value = 121, the cycle is done and I can collect the data.

For the interaction with the motor, it will be done by grounding a pin in the parallel port.I do not need help with the motor control, only the n value need to be synchronized with the datagrid.Please refer to the attached pics. I used Winspector to get the class of the datagrid. It is in the red box.