SC32B Optically Isolated RS-232 Interface


The SC32B Optically Isolated Interface is used to connect the CS I/O port on a data logger with the RS-232 port on a PC. This interface converts the RS-232 voltage levels of the computer to the CMOS levels of the data logger. It also isolates the electrical system of the computer from the data logger, thereby protecting against ground loop, normal static discharge, and noise.

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Benefits and Features

  • Connects a PC to the CS I/O port of a data logger
  • Helps protect components from electrical damage
  • No power source needed—powered by data logger and PC
  • Ships with cables needed for most uses
  • Baud rates up to 115 kbps supported



Baud Rates Supported Up to 115 kbps
Power Drawn from the serial ports of the PC and data logger
Typical Current Drain
  • < 200 µA (quiescent)
  • ~15 mA (active)
Connections 9-pin RS-232 female port configured as DCE; 9-pin male port
Operating Temperature Range -25° to +50°C
Dimensions 4.1 x 2.3 x 7.6 cm (1.6 x 0.9 x 3.0 in.)
Weight 45.4 g (1.6 oz)


Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.

Data Loggers

Compatible Note
21X (retired)
CR10 (retired)
CR1000 (retired)
CR10X (retired)
CR200X (retired)
CR206X (retired)
CR23X (retired)
CR295X (retired)
CR500 (retired)
CR5000 (retired)
CR510 (retired)
CR9000 (retired)
CR9000X (retired)

Additional Compatibility Information

Data Logger Considerations

An interface such as the SC32B is required for direct communications between a PC and data loggers that only have a CS I/O port. For our CR800, CR850, and CR1000 dataloggers, the SC32B is often used to provide optical isolation between the data logger and PC. Although the on-board RS-232 port of the CR3000, CR5000, or CR9000X dataloggers is isolated, the SC32B can be interfaced with their CS I/O port when a second RS-232 port is required in the application.

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Replacement Part for the following products:

FAQs for

Number of FAQs related to SC32B: 14

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  1. Because the SC-USB includes a processor, it costs more to manufacture than the SC32B.
  2. No. The SC32B cannot be used at the same time as an SDC device. The SC32B is a modem-enabled device and is not capable of concurrent communication.
  3. Yes. It ships with both the SC12 and 10873 serial cables. Usually, the SC12 is connected to the data logger, and the 10873 is connected to the computer.

  4. Non-isolated interfaces (that is, connection to the RS-232 port with a standard serial cable connection) can cause ground offset errors in analog measurements using a system connected to a PC and powered by an ac source. The SC32B provides isolation that may be important when recording low-level, single-ended voltage measurements.

  5. No, because it would not work. The SC32B is used to do the following:

    • Convert data logger logic levels (on the CS I/O port) to RS-232 levels 
    • Optically isolate the data logger from the RS-232 peripheral 
  6. The SC929 has been functionally replaced by the SC32B. While the SC929 is still available, the SC32B has increased capability at a reduced cost. See the table for a comparison:




      Optically Isolated



      Maximum Baud



      Current Draw

      8 mA

      Active < 200 µA

    Cables are an additional comparison point for these two products:

    • The SC929 cable directly connects the PC to the data logger’s CS I/O port.
    • The SC32B interface typically uses the 10873 serial cable to connect to the PC and the SC12 cable to connect to the CS I/O port. Both of these cables are shipped with the SC32B.
  7. There are several differences:

    • The SC32A requires a 25-pin serial cable between the computer and interface. The SC32B, on the other hand, has DB9 connectors for both the data logger and computer side.
    • The SC32B cannot be configured to pass serial printer or computer data.

    For comparisons, see the SC32A product page and the SC32B product page.

  8. 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.

  9. 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