6.1. USB Interface

The USB interface provides a convenient way to connect to most modern computers. The USB interface is implemented as a virtual serial com port connection. This implementation provides a simple migration path for modifying existing RS-232 based remote interface software. It also provides a simpler means of communicating than a standard USB implementation.

Physical Connection

The M81-SSM has a B-type USB connector on the rear panel. This is the standard connector used on USB peripheral devices, and it allows the common USB A-type to B-type cable to be used to connect the M81-SSM to a host PC. The pin assignments for A-type and B-type connectors are shown in section 6.7. The maximum length of a USB cable, as defined by the USB 2.0 standard, is 5 m (16.4 ft). This length can be extended using USB hubs every 5 m (16.4 ft) up to five times, for a maximum total length of 30 m (98.4 ft).

Note

The M81-SSM also has a USB-C connector for firmware updates. Only the USB-B connection can be used for SCPI commands.

Hardware Support

The USB interface emulates an RS-232 serial port at a fixed 921,600 baud rate, but with the physical connections of a USB. This programming interface requires a certain configuration to communicate properly with the M81-SSM. The proper configuration parameters are listed in the table below.

Baud rate

921600

Data bits

8

Parity

None

Stop bits

1

Flow control

RTS/CTS

Command terminator

LF (CR ignored)

Query response terminator

CR LF

The USB hardware connection uses the full speed (12,000,000 bit/s) profile of the USB 2.0 standard; however, since the interface uses a virtual serial com port at a fixed data rate, the data throughput is still limited to a baud rate of 921,600 bit/s.

Driver Installation

Installing the Driver from Windows® Update

The USB driver is available through Windows® Update. This is the recommended method for installing the driver, as it will ensure that you always have the latest version of the driver installed.

  1. Connect the USB cable from the M81-SSM to the computer.

  2. Turn on the M81-SSM.

  3. When the Found New Hardware wizard appears, select Locate and install driver software (recommended).

  4. The Found New Hardware wizard should automatically connect to Windows® Update and install the drivers.

  5. When the Found New Hardware wizard finishes installing the driver, a confirmation message stating “the software for this device has been successfully installed” will appear. Click Close to complete the installation.

Installing the Driver from the Web

If you are unable to install the driver from Windows® Update, refer to the instructions below to install the driver from the web. These procedures assume that you are logged into a user account that has administrator privileges.

The USB driver is available on the Lake Shore website. To install the driver, it must be downloaded from the website and extracted. Use the procedures below to download, extract, and install the driver using Windows®.

Download the driver

  1. Locate the USB driver from https://www.lakeshore.com/resources/software.

  2. Right-click on the USB driver download link, and select Save as.

  3. Save the driver to a convenient place, and take note where the driver was downloaded.

Extract the driver

The downloaded driver is in a ZIP compressed archive. The driver must be extracted from this file. Windows® provides built-in support for ZIP archives. If this support is disabled, a third-party application, such as WinZip™ or 7-Zip, must be used.

  1. Right-click on the file and click extract all.

  2. An Extract Compressed (Zipped) Folders dialog box will appear. It is recommended the default folder is not changed. Take note of this folder location.

  3. Click to clear the Show extracted files when complete checkbox, and click Extract.

Manually install the driver

The following section describes how to manually install the driver using Windows®. To install the driver, you must be logged in to a user account that has administrator privileges.

  1. Connect the USB cable from the M81-SSM to the computer.

  2. Turn on the M81-SSM.

  3. If the Found New Hardware wizard appears, click Ask me again later.

  4. Open Device Manager. Use this procedure to open Device Manager.

    1. Click the Windows® Start button and type Device Manager in the Start Search box.

    2. Click on the Device Manager link in the Search Results Under Programs dialog box.

    3. If User Account Control is enabled click Continue on the User Account Control prompt.

  5. Click View and ensure the Devices by Type check box is selected.

  6. In the main window of Device Manager, locate Other Devices in the list of device types. In many instances this will be between Network adapters and Ports (COM & LPT). If the Other Devices item is not already expanded, click the + icon. M81-SSM should appear indented underneath Other Devices. If it is not displayed as M81-SSM, it might be displayed as USB Device. If neither are displayed, click Action and then Scan for hardware changes, which may open the Found New Hardware wizard automatically. If the Found New Hardware wizard opens, click Cancel.

  7. Right-click M81-SSM and click Update Driver Software.

  8. Click Browse my computer for driver software.

  9. Click Browse and select the location of the extracted driver.

  10. Ensure the Include subfolders check box is selected and click Next.

  11. When the driver finishes installing a confirmation message stating “Windows has successfully updated your driver software” should appear. Click Close to complete the installation.