FoxPro/Visual FoxPro - traducir codigo vb a vfp

tengo el sig codigo que quiero saber exactamente que hace para hacerlo en vfp
se que esta declarando funciones que vienen incluidas en una api dll pero la segunda parte no la entiendo bien (lo de ByVal, ByRef)
espero me puedan ayudar un saludo

Public Declare Function VB_seleccionarIdioma Lib "BanortePinPad.dll" _
(ByVal idioma As String, ByRef excep As Variant) As Integer

Public Declare Function VB_selectLanguage Lib "BanortePinPad.dll" _
(ByVal language As String, ByRef excep As Variant) As Integer

Public Declare Function VB_inicializarDispositivo Lib "BanortePinPad.dll" _
(ByVal tipo As String, ByRef config As Variant, ByRef excep As Variant) As Integer

Public Declare Function VB_prepareDevice Lib "BanortePinPad.dll" _
(ByVal pinpadType As String, ByRef inputMap As Variant, ByRef excep As Variant)
As Integer

Public Declare Function VB_liberarDispositivo Lib "BanortePinPad.dll" _
(ByRef excep As Variant) As Integer

Public Declare Function VB_releaseDevice Lib "BanortePinPad.dll" _
(ByRef excep As Variant) As Integer

Public Declare Function VB_desplegarTexto Lib "BanortePinPad.dll" _
(ByVal texto As String, ByRef excep As Variant) As Integer

Public Declare Function VB_displayText Lib "BanortePinPad.dll" _
(ByVal text As String, ByRef excep As Variant) As Integer

en google hay varios programitas que te hacen la conversion