SC32B Optically Isolated RS-232 Interface

Overview

The SC32B Optically Isolated Interface is used to connect the CS I/O port on a datalogger 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 datalogger. It also isolates the electrical system of the computer from the datalogger, 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 datalogger
  • Helps protect components from electrical damage
  • No power source needed—powered by datalogger and PC
  • Ships with cables needed for most uses
  • Baud rates up to 115 kbps supported

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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 datalogger 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 cable for attachment to the datalogger and a 10873 cable for attachment to the PC. Alternatively, an SC12R-6 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 datalogger 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 datalogger
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)

Compatibility

Datalogger Considerations

An interface such as the SC32B is required for direct communications between a PC and dataloggers 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 datalogger 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.

Compatible Contemporary Dataloggers

CR200(X) Series CR800/
CR850
CR1000 CR3000 CR6 CR9000X CR1000X

Compatible Retired Dataloggers

CR500 CR510 CR10 CR10X 21X CR23X CR9000 CR5000 CR7X
*

Notes:
*The retired CR9000 requires a CR9080 PAM module.


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. 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 datalogger, 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 datalogger logic levels (on the CS I/O port) to RS-232 levels 
    • Optically isolate the datalogger 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:

     

      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 datalogger’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. This is not necessarily an error associated with the SC32B. The message means that an attempt to check or set the clock on a mixed-array datalogger (CR10, CR21X, CR7X, CR10X, CR510, and CR23X) failed. There could be several reasons for this error.
  8. 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 datalogger 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.

  9. 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 datalogger with a CS I/O port.