S2USB485 Interface USB to RS485 / RS232 / N2 Interface



The S2USB485 is a USB to full-duplex RS-232 and half-duplex RS-485 serial converter integrated into a single device.  In essence the S2USB485 is a single USB serial port that has two electrical interfaces available to it (RS-232 and RS-485).  Either interface can be used without the need to set jumpers or change dip switch settings.



The S2USB485 can be used as a replacement to the Johnson Controls MM-CVT101 (RS-232 to N2 Bus) / CVTPro100 converter for those computers or laptops that have a USB interface.  In addition to direct support for Johnson Controls software (Metasys, HVAC Pro, etc), the S2USB485 provides the following improved features and functionality:

  • USB interface and so is supported by the latest laptops and operating systems
  • Does not require an external power supply.  The device is entirely USB interface powered
  • Incorporates both a RS-232C and N2 (RS-485) bus interface so that multiple converters are not necessary.
  • N2 Bus communication is supported under Windows 7 (32/64 bit), XP, 2000 directly.
  • Transmit and Receive Indicators
  • N2 Bus flow control internally controlled (i.e. no jumpers or resistors to add/modify)
  • N2 Bus has end of line termination (EOL) enabled or disabled by an internal slide switch
  • Designed and Manufactured in Canada using Industrial grade components
  • ZoneBus is not officially supported.
  • ROHS Compliant
  • New Version (July 2008) now has enhanced overvoltage protection and internal auto reset-able thermal fuses in the event of high voltages present on the RS485 / N2 bus
  • New Version (July 2008) includes enhanced mechanical rigidity of the RS485/N2 bus connector
  • New Version (July 2008) includes OBD (On-Board Diagnostics) of the RS485/N2 Bus.  OBD allows our S2USB485DiagN2 software to electrically  analyze (voltage measuring) the RS485/N2 bus and indicate electrical issues to the user.
  • As of July 2008, the anchored cable version of the S2USB485 (part number S2USB485-JC-C) has been reluctantly discontinued do to the quality issues with our anchored cable manufacturer.  Only the S2USB485-JC-B is now offered with or without the required USB cable (a Type A to Type B).
  • New Version (July 2008) Pricing has been maintained for this enhanced S2USB485  version.  The included cable version is priced the same as the old anchored cable version
  • Vista Tested and Compatible
  • Tested and compatible with JCI's HVACPro and JCI's FX CommPro
  • Windows 7 Compatible. Please see the two installation documents on the right for the procedure for using HVACPro/CommPro under Windows 7 
  • Windows 8 - Compatible Drivers have been released.  They are located below under latest Drivers.  
  • Windows 8  - JCI software tools such as HVACPro, etc do not to work under Windows 8 Natively.   Windows 7 has XP mode which allowed for legacy applications to be used, but Windows 8 currently does not have an XP mode equivalent.  It is recommended that HVACPro users, etc continue to use Windows XP or Windows 7 with XP Mode (only available with Windows 7 Pro or Ultimate). If you need to use Windows 8 with JCI Software tools you need to install a Licensed copy of Windows XP in your preferred Virtualuzation software (i.e. Virtual Box, VMWare, etc) under Windows 8.  


Click here to for our Free N2 bus Diagnostic Utility

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Part Number:

  • S2USB485-JC-B: USB type B Recepticle Only (No Cable)
  • S2USB485-JC-CB: A S2USB485-JC-B but includes the required USB cable; cable: 2 Metre (6 feet) USB 2.0 Type A to Type B Cable

Supported Operating Systems:

  • Windows  8 (Prerelease)
  • Windows  7 32/64 Bit
  • Windows Vista
  • Windows XP

Power Requirements:

  • USB Powered, maximum of 225 mA

Data Rates:

  • RS-485: 300 to 1 MBaud
  • RS-232: 300 to 3 MBaud
  • Temperature 0 C to +60 C
  • Humidity: 10 - 95 % RH (non-condensing)

Data Interfaces:

  • USB: USB 1.1/2.0 Compatible

  • RS-485: Half Duplex, 1 Unit Load, 3-Pin Connector
  • RS-232C: DB-9 Male Connector


  • 2.6”L x 2.6”W x 1.1” H  
  • 6.6cm L x 6.6cm W x 2.8cm H