SC32B Optically Isolated RS-232 Interface

Overview

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

Images

Right view
SC32B with included 10873 and SC12 cables (other items sold separately)

Detailed Description

The SC32B, or another interface, is required for direct communications between a PC and a CR510, CR10X, or CR7 datalogger. For our CR800, CR850, CR1000, and CR1000X 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.

The SC32B is shipped with an SC12 (2 ft) cable for attachment to the data logger and a 10873 (6 ft) cable for attachment to the PC. Alternatively, an SC12R-6 (6 ft) cable (purchased separately) can be used instead of the standard SC12 when a longer cable is needed.

The SC32B can support RS-232 cable lengths of up to 50 feet; longer cable lengths are not recommended. The longer cable should be on the data logger side of the interface (CMOS logic levels) as opposed to the RS-232 side, which is typically more sensitive to drops in signal voltage levels.

Specifications

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 socket (female) port configured as DCE; 9-pin 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)

Compatibility

Note: The following shows notable compatibility information. It is not a comprehensive list of all compatible or incompatible products.

Data Loggers

Product Compatible Note
21X (retired)
CR10 (retired)
CR1000 (retired)
CR1000X
CR10X (retired)
CR200X (retired)
CR206X (retired)
CR211X (retired)
CR216X (retired)
CR23X (retired)
CR295X (retired)
CR3000 (retired)
CR500 (retired)
CR5000 (retired)
CR510 (retired)
CR6
CR800 (retired)
CR850 (retired)
CR9000 (retired) The CR9000 requires a CR9080 PAM module.
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.


Frequently Asked Questions

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. 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.

  3. 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.
  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. 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.

  7. See the table for a detailed comparison:

     

     17394
     USB-serial  cable

     SC32B

     SC929

     SC-USB

     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

     Connectors

     USB A male –  9-pin male

     9-pin male – 9-pin  female

     9-pin male – 9-pin  female

     USB B female –  9-pin male

     Length

     6 ft

     3 in.

     6 ft

     1.6 in.

     Power  Consumption

     N/A

     Active <200 a="" --200--="">

     8 mA continuous

     Active <20 ma="" --20--="">

     Optically  Isolated

     No

     Yes

     No

     Yes

     Operating  Temperature

     N/A

     -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

  8. 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.

  9. 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:

     

      SC929

      SC32B

      Optically Isolated

      No

      Yes

      Maximum Baud

      9600

      115200

      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.

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