VBS script to login to SAP 

 Set WshShell = CreateObject("WScript.Shell")

Set proc = WshShell.Exec("C:\Program Files (x86)\SAP\FrontEnd\SAPgui\saplogon.exe")

WScript.Sleep 4000

Set SapGui = GetObject("SAPGUI")

Set application = SapGui.GetScriptingEngine

Set connection = application.OpenConnection("SAP System Name as per GUI", True)

Set Session = connection.children(0)

session.findById("wnd[0]/usr/txtRSYST-BNAME").text = "USERID"

session.findById("wnd[0]/usr/pwdRSYST-BCODE").text = "PASSWORD"

session.findById("wnd[0]").sendVKey 0