Future Technology Devices International Ltd
USB NMC-2.5m
USB to USB Null Modem Cable
Datasheet
Document Reference No.: FT_000054
Version 1.00
Issue Date: 2008-07-16
Future Technology Devices International Ltd (FTDI)
373 Scotland Street, Glasgow G5 8QB United Kingdom
Tel.: +44 (0) 141 429 2777

Fax: + 44 (0) 141 429 2758

E-Mail (Support): support1@ftdichip.com Web: http://www.ftdichip.com

Neither the whole nor any part of the information contained in, or the product described in this manual, may be adapted or reproduced in any
material or electronic form without the prior written consent of the copyright holder. This product and its documentation are supplied on an as-isbasis and no warranty as to their suitability for any particular purpose is either made or implied. Future Technology Devices International Ltd
will not accept any claim for damages howsoever arising as a result of use or failure of this product. Your statutory rights are not affected. This
product or any variant of it is not intended for use in any medical appliance, device or system in which the failure of the product mightreasonably be expected to result in personal injury. This document provides preliminary information that may be subject to change without
notice. No freedom to use patents or other intellectual property rights is implied by the publication of this document. Future Technology Devices
International Ltd, 373 Scotland Street, Glasgow G5 8QB United Kingdom. Scotland Registered Number: SC136640

Copyright © 2008 Future Technology Devices International Limited

Document Reference No.: FT_000056
USB NMC-2.5m USB To USB Null Modem Cable Datasheet Version 1.00
Clearance No.: FTDI# 40

1Description

The USB to USB Null Modem Cable is a modern replacement for the traditional serial null modem cable. The
traditional null modem cable was used to connect two PCs via their RS232 serial ports, but fewer modern
PCs continue to implement the RS232 serial port. The RS232 port has almost entirely been replaced by theUSB port.
However there is still a need to transfer files between PCs that are not networked.
The FTDI USB Null Modem Cable (NMC) solves this problem and allows a user to connect two PCs using
their USB ports. The user can then perform file transfers between the PCs via the USB interface.
The NMC cable contains a small internal electronic circuit board encapsulated into the USB connector atboth ends of the cable. The electronics is based on the FTDI FT232R USB to Serial UART IC and handles
all the USB signalling and protocols. The FT232R datasheet, DS_FT232R, is available at
http://www.ftdichip.com
The NMC cable is a USB powered, USB 2.0 full speed compatible, 2.5m cable which supports data transfer
rate up to 3 Mbaud at TTL levels. The NMC cable supports the FTDIChip-ID™, with each cable end
programmed with a unique USB serial number. This can be used to create security or password protected
file transfer between PCs. Further information and examples on this feature are available at
http://www.ftdichip.com under FTDIChip-ID Projects.
The cable requires USB drivers, available free from http://www.ftdichip.com, which are used to make theFT232R within the cable ends appear as a virtual COM port (VCP). This then allows the user tocommunicate with the USB interface via a standard PC serial emulation port (TTY). Another FTDI USB
driver, the D2XX driver, can also be used with application software to directly access the FT232R though aDLL. This is illustrated in the Figure 1.1:

USB_USB_NMCTTYUSB

TTYUSB

Virtual COM Port

USB_USB_NMC

TTYTTYUSBUSB

Software application access to USB via D2XX
Figure 1.1 USB to USB Null Modem Cable Example

The NMC maximum operating current is 20mA (per USB connector), with a very small USB suspend current(70µA).
The cable is fully FCC and CE compliant and operates over an extended temperature range.

Copyright © Future Technology Devices International Limited1

Document Reference No.: FT_000056
USB NMC-2.5m USB To USB Null Modem Cable Datasheet Version 1.00
Clearance No.: FTDI# 40

Table of Contents
1Description ............................................................................................. 12

Typical Applications .............................................................................. 332.1

Driver Support ..................................................................................................... 32.2Features ............................................................................................................... 3

Contact Information............................................................................... 4
Appendix A - FT232R EEPROM Configuration ............................................................ 5
Appendix B - Revision History ...................................................................................... 6

Copyright © Future Technology Devices International Limited

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USB NMC-2.5m USB To USB Null Modem Cable Datasheet Version 1.00
Clearance No.: FTDI# 402

Typical Applications•

PC to PC networking using USB port.

•File transfer between PCs.

•Password protected file transfer between PCs.

2.1

Driver Support

Royalty free VIRTUAL COM PORT(VCP) DRIVERS for...

Royalty free D2XX Direct Drivers(USB Drivers + DLL S/W Interface)•

Windows 98, 98SE, ME, 2000, Server 2003, XPand Server 2008•

Windows 98, 98SE, ME, 2000, Server 2003, XPand Server 2008•

Windows XP and XP 64-bit•Windows XP and XP 64-bit•

Windows Vista and Vista 64-bit•

Windows Vista and Vista 64-bit•

Windows XP Embedded•

Windows XP Embedded•

Windows CE 4.2, 5.0 and 6.0•

Windows CE 4.2, 5.0 and 6.0•

Mac OS 8/9, OS-X•

Linux 2.4 and greater•

Linux 2.4 and greater

The drivers listed above are all available to download for free from www.ftdichip.com. Various 3rd Party
Drivers are also available for various other operating systems - see www.ftdichip.com for details.

2.2Features

The USB NMC has the following features:•

USB powered – no external power supply
needed.

•Improved EMI Performance - FCC and CE
compliant.

•Based on back to back FTDI FT232RQ devices.

••Entire USB protocol handled by USB connector
encapsulated electronics.

Supports FT232R FTDIChip-ID™, with eachcable end programmed with a unique USB serialnumber.

•

USB Type A connector on both ends of cable.

•

Support for USB suspend and resume.

•Data transfer rates from 300 baud to 3 Mbaud atTTL levels.

•

UHCI / OHCI / EHCI host controller compatible.

•

USB 2.0 Full Speed compatible.

•Custom versions also available (subject toMOQ).

•-40°C to +85° C operating temperature range.

•Lower Operating (20mA) and USB suspendmode current (70µA).

Copyright © Future Technology Devices International Limited

3Document Reference No.: FT_000056
USB NMC-2.5m USB To USB Null Modem Cable Datasheet Version 1.00
Clearance No.: FTDI# 40

3Contact Information

Head Office – Glasgow, UK
Future Technology Devices International Limited
373 Scotland Street
Glasgow G5 8QB
United Kingdom
Tel: +44 (0) 141 429 2777
Fax: +44 (0) 141 429 2758
E-mail (Sales)
sales1@ftdichip.com
E-mail (Support) support1@ftdichip.com
E-mail (General Enquiries) admin1@ftdichip.com
Web Site URL
http://www.ftdichip.com
Web Shop URL http://www.ftdichip.com

Branch Office – Taipei, Taiwan
Future Technology Devices International Limited (Taiwan)
4F, No 18-3, Sec. 6 Mincyuan East Road
Neihu District
Taipei 114
Taiwan, R.O.C.
Tel: +886 (0) 2 8791 3570
Fax: +886 (0) 2 8791 3576
E-mail (Sales)
tw.sales1@ftdichip.com
E-mail (Support) tw.support1@ftdichip.com
E-mail (General Enquiries) tw.admin1@ftdichip.com
Web Site URL
http://www.ftdichip.com

Branch Office – Hillsboro, Oregon, USA
Future Technology Devices International Limited (USA)7235 NW Evergreen Parkway, Suite 600
Hillsboro, OR 97123-5803
USA
Tel: +1 (503) 547 0988
Fax: +1 (503) 547 0987
E-Mail (Sales)
E-Mail (Support)
Web Site URL

us.sales@ftdichip.com
us.admin@ftdichip.com
http://www.ftdichip.com

Distributor and Sales Representatives
Please visit the Sales Network page of the FTDI Web site for the contact details of our distributor(s) andsales representative(s) in your country.

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Document Reference No.: FT_000056
USB NMC-2.5m USB To USB Null Modem Cable Datasheet Version 1.00
Clearance No.: FTDI# 40

Appendix A - FT232R EEPROM Configuration
Each end of the NMC cable is controlled by the FTDI FT232R IC. This FT232R device contains an EEPROM
which contains the USB configuration descriptors for that device. When the cable is plugged into a PC or a
USB reset is performed, the PC will read these descriptors. The default values stored into the internal
EEPROM are defined in Error! Reference source not found..

Parameter

ValueNotes

USB Vendor ID (VID)

0403h

FTDI default VID (hex)

USB Product UD (PID)

6001h

FTDI default PID (hex)Serial Number Enabled?

Yes

Serial NumberSee Note

Pull down I/O Pins in USB SuspendDisabled

Manufacturer Name

FTDI

Product Description

USB Null Modem Cable

Max Bus Power Current

A unique serial number is generated and programmed into theEEPROM during device final test.
Enabling this option will make the device pull down on the UART
interface lines when the power is shut off (PWREN# is high).

90mA

Power Source

Bus PoweredDevice TypeFT232R
Returns USB 2.0 device description to the host.

USB Version

0200

Note: The device is be a USB 2.0 Full Speed device (12Mb/s) as
opposed to a USB 2.0 High Speed device (480Mb/s).

Remote Wake Up

Disabled

Taking RI# low will wake up the USB host controller from suspend.

High Current I/Os

Disabled

Enables the high drive level on the UART and CBUS I/O pins.

Load VCP Driver

Disabled

Makes the device load the VCP driver interface for the device.

Invert TXDDisabled

Signal on this pin becomes TXD# if enable.

Invert RXD

Disabled

Signal on this pin becomes RXD# if enable.

Invert RTS#

Disabled

Signal on this pin becomes RTS if enable.

Invert CTS#Disabled

Signal on this pin becomes CTS if enable.

Table 3.1 Default Internal EEPROM Configuration

The internal EEPROM in the FT232R can be re-programmed over USB using the utility program MPROG.
MPROG can be downloaded from the www.ftdichip.com. Version 2.8a or later is required for the FT232R
chip. Users who do not have their own USB Vendor ID but who would like to use a unique Product ID in theirdesign can apply to FTDI for a free block of unique PIDs. Contact FTDI support for this service.

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Document Reference No.: FT_000056
USB NMC-2.5m USB To USB Null Modem Cable Datasheet Version 1.00
Clearance No.: FTDI# 40

Appendix B - Revision History
Version 1.00

Full datasheet released

Copyright © Future Technology Devices International LimitedJuly 20086