Windows 7 has no CDC built-in support, however it is easy to add one. Save this:
;
; Comunication Device Class driver installation file
; Provided by Ceat
;
[Version]
Signature="$Windows NT$"
Class=Ports
ClassGuid={4D36E978-E325-11CE-BFC1-08002BE10318}
Provider=%ZWO%
LayoutFile=layout.inf
DriverVer=1/05/23
[Manufacturer]
%ZWO%=DeviceList,NTamd64
[DestinationDirs]
DefaultDestDir=12
;------------------------------------------------------------------------------
; VID/PID Settings
;------------------------------------------------------------------------------
[SourceDisksFiles]
[SourceDisksNames]
[DeviceList]
%DESCRIPTION%=DriverInstall, USB\VID_03C3&PID_4001
[DeviceList.NTamd64]
%DESCRIPTION%=DriverInstall, USB\VID_03C3&PID_4001
;------------------------------------------------------------------------------
; Windows 2000/XP/Vista32/Win7_32 Sections
;------------------------------------------------------------------------------
[DriverInstall.nt]
include=mdmcpq.inf
CopyFiles=DriverCopyFiles
AddReg=DriverInstall.nt.AddReg
[DriverCopyFiles]
usbser.sys,,,0x20
[DriverInstall.nt.AddReg]
HKR,,DevLoader,,*ntkern
HKR,,NTMPDriver,,usbser.sys
HKR,,EnumPropPages32,,"MsPorts.dll,SerialPortPropPageProvider"
[DriverInstall.nt.Services]
include=mdmcpq.inf
AddService=usbser, 0x00000002, DriverService
[DriverInstall.nt.HW]
include=mdmcpq.inf
[DriverService]
DisplayName=%DESCRIPTION%
ServiceType=1
StartType=3
ErrorControl=1
ServiceBinary=%12%\usbser.sys
;------------------------------------------------------------------------------
; Windows Vista_64/Win7_64 Sections
;------------------------------------------------------------------------------
[DriverInstall.NTamd64]
include=mdmcpq.inf
CopyFiles=DriverCopyFiles.NTamd64
AddReg=DriverInstall.NTamd64.AddReg
[DriverCopyFiles.NTamd64]
usbser.sys,,,0x20
[DriverInstall.NTamd64.AddReg]
HKR,,DevLoader,,*ntkern
HKR,,NTMPDriver,,usbser.sys
HKR,,EnumPropPages32,,"MsPorts.dll,SerialPortPropPageProvider"
[DriverInstall.NTamd64.Services]
AddService=usbser, 0x00000002, DriverService.NTamd64
[DriverService.NTamd64]
DisplayName=%DESCRIPTION%
ServiceType=1
StartType=3
ErrorControl=1
ServiceBinary=%12%\usbser.sys
;------------------------------------------------------------------------------
; String Definitions
;------------------------------------------------------------------------------
[Strings]
ZWO="ZWO"
DESCRIPTION="ZWO AM5 CDC driver"
to AM5.inf file, then in Device Manager select Install Driver and point to this file. Your AM5 should then be visible as a COM port.