valores maximos: 99:59;59;999
Código
Option Explicit Private Sub Form_Load() MsgBox SumarTiempo("00:02;20.254", "00:02;59.800") End Sub Private Function SumarTiempo(Tiempo1 As String, Tiempo2 As String) As String Dim H As Integer, H2 As Integer Dim M As Integer, M2 As Integer Dim S As Integer, S2 As Integer Dim Ml As Integer, Ml2 As Integer Dim Horas As Integer, Minutos As Integer, Segundos As Integer, Milesimas As Integer H = Mid(Tiempo1, 1, 2) M = Mid(Tiempo1, 4, 2) S = Mid(Tiempo1, 7, 2) Ml = Mid(Tiempo1, 10, 3) H2 = Mid(Tiempo2, 1, 2) M2 = Mid(Tiempo2, 4, 2) S2 = Mid(Tiempo2, 7, 2) Ml2 = Mid(Tiempo2, 10, 3) Horas = H + H2 Minutos = M + M2 Segundos = S + S2 Milesimas = Ml + Ml2 If Milesimas >= 1000 Then Segundos = Segundos + 1 Milesimas = Milesimas - 1000 End If If Segundos >= 60 Then Minutos = Minutos + 1 Segundos = Segundos - 60 End If If Minutos >= 60 Then Horas = Horas + 1 Minutos = Minutos - 60 End If SumarTiempo = Format(Horas, "00") & ":" & Format(Minutos, "00") & ";" & Format(Segundos, "00") & "." & Format(Milesimas, "000") End Function
espero que te sirva de algo. Saludos xD