Thanks for all the help guys.

Based on the examples you provided i've ended up with this for operating my drawbar:

If GetOEMLED(11) Then
Message("Spindle Must Be OFF to Change Tool!!")
ElseIf GetOEMLED(852) Then
DeActivateSignal(OUTPUT1)
Message("Tool Locked")
Else
ActivateSignal(OUTPUT1)
Message("Tool Released")
End If