L17394 Converter, USB to DB9 Male RS-232


The 17394 is a six-foot interface cable fitted with a USB connector on one end and a 9-pin male RS-232 connector on the other end. The USB connector attaches to the USB port of a PC. The RS-232 connector attaches to the RS-232 port of a data logger or peripheral, such as an MD485 Multidrop Modem or RF401-series Spread-Spectrum Radio. Alternatively, the RS-232 connector can attach to an SC32B interface, which attaches to the CS I/O port of a data logger via the SC12 cable.

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Cable Diameter 4 mm (0.2 in.)
Cable Length 2 m (6 ft)
  • 6.6 x 4.0 x 2.3 cm (2.75 x 1.7 x 0.9 in.) for 9-pin connector
  • 5.5 x 1.6 x 0.9 cm (2.17 x 0.7 x 0.4 in.) for USB connector
Weight 73 g (2.6 oz)


Computer Operating Systems

  • Cables that shipped after February 20, 2013 use the FTDI chip set and are all black in appearance. These cables are compatible with Windows XP, Vista, 7, 8, 10, and Mac OS X.
  • Cables that shipped before February 20, 2013 use the Prolific chip set and have a clear and metallic appearance. These cables are NOT compatible with Windows 8 and above.


The 17394 is compatible with any device that has an RS-232 port. It can also connect to the data logger's CS I/O port via the SC32B interface, and connect to some peripherals via the SC532A interface.


Retired - USB to Serial Driver (Prolific Chip Set) v. (7.98 MB) 21-09-2012

This driver is for the SBT-USC6K USB to Serial cable (CSI Part# 17394 - Silver Cable). Support is for Windows XP/Vista/7.  This driver is not compatible with Windows 8 and above or the SC-USB Interface.

Note: Install the driver before plugging the cable into your computer.  Once the driver has been installed, plug the cable into the computer to finish the installation.

FAQs for

Number of FAQs related to L17394: 7

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  1. A USB-to-serial cable has electronic components in it to interface the USB to the RS-232. There is no pin correlation between USB and DB9.

  2. The combination of the USB to serial (17394) and the SC32B is basically the same as the SC-USB. Both options enable communication between a computer and a data logger with a CS I/O port.

  3. See the table for a detailed comparison:


     USB-serial  cable




     Useful for  Connecting

     PC USB port to  data logger RS-  232 port

     Data logger CS  I/O  port to laptop  COM  port

     Data logger CS  I/O  port to laptop  COM  port

     Data logger CS  I/O  port to PC  USB  port


     USB A male –  9-pin male

     9-pin male – 9-pin  female

     9-pin male – 9-pin  female

     USB B female –  9-pin male


     6 ft

     3 in.

     6 ft

     1.6 in.

     Power  Consumption


     Active <200 a="" --200--="">

     8 mA continuous

     Active <20 ma="" --20--="">

     Optically  Isolated





     Operating  Temperature


     -25° to +50°C

     -25° to +50°C

     -25° to +50°C

     Maximum Data  Transfer Rate

     1 Mbps USB

     115200 bps

    9600 bps

     1 Mbps USB

  4. Many of our more recent data loggers have a Micro B USB port. Simply use a Type A to Micro B, male-to-male cable. Although any USB cable, with the correct connectors and drivers, should work, there is a better chance of success using a cable supplied by Campbell Scientific.

    For data loggers with an RS-232 port, only a serial or USB to RS-232 cable (sometimes called a USB-to-serial-adapter cable) is needed. Although any USB to RS-232 cable should work with the appropriate drivers, there is a better chance of success using the USB to RS-232 cables sold by Campbell Scientific.

    There are several options for data loggers that don’t have an RS-232 port but have a CSI/O port:

    1. Use the SC-USB connector/interface instead of the SC32B.
    2. Use the SC32B with a 17394, USB-to-9-pin male RS-232 cable.
    3. Use a user-supplied USB interface with the SC32B.

    For data loggers with a CSI/O and RS-232 or USB port, it is not necessary to use the SC32B unless there is another device connected to the RS-232 port or there are concerns about low-level noise from a permanently connected, ac-powered computer.

  5. Some possible causes include the following:

    • The result of a hardware condition in the data logger or the port driver
    • Incorrect USB drivers (Even if the correct drivers have been successfully installed, the errors may still be related to the cable.)
      • Note: Not all USB-to-serial cables are the same. Although any USB to RS-232 cable should work with the appropriate drivers, there is a better chance of success using the USB to RS-232 cables sold by Campbell Scientific. Cables that are not purchased from Campbell Scientific have not been tested and may result in errors when connecting to a data logger. Furthermore, USB-to-serial cables with the FTDI chipset are easier to use and seem to perform better than cables with the Prolific chipset.
    • Power supply or grounding issues on the data logger
    • The port configuration of the data logger (If the data logger RS-232 port is configured at a fixed baud rate other than 115200, it might cause the error messages.)

    The Device Configuration Utility, under its Unknown device type, has an Identify Logger Type button. This button will attempt to identify the device type, protocol, or both used for the data logger and will attempt to do so at various baud rates. If the data logger is synchronized with a different baud rate or is set up at a fixed baud rate, this feature may provide the means of determining what baud rate should be used for successful communication. 

  6. Communication through the data logger’s CS I/O port requires an interface that converts the computer’s RS-232 voltage levels to the CMOS levels of the data logger. Typically, that interface is an SC32B. The SC32B connects to the data logger’s CS I/O port via an SC12 or serial cable and connects to a computer’s 9-pin serial port via a serial cable. When the computer does not have a serial port, a 9-pin serial-to-USB cable, such as pn 17394, can be used with the SC32B. Alternatively, instead of the SC32B, use the SC-USB.