Badly-Formed IDN String

Problem:

Your instrument returns a badly-formed IDN (identification) string. This may be indicated in Connection Expert by a icon by the instrument's address in the right pane of the Instruments view.

Probable Causes and Suggested Steps:

There are several reasons for an instrument to return badly-formed IDN strings.

  • It may be that the instrument does not conform to the IEEE 488.2 standard for instrument communications, and therefore does not understand the *IDN? identification query sent by Connection Expert.

    1. If you are unsure, check your instrument documentation to determine its 488.2 compliance.

    2. Some instruments support multiple languages, or personalities, some of which support 488.2 while others do not. For example, the Keysight 34401A digital multimeter has a Language menu option that can be set to SCPI, HP 3478A emulation, or Fluke 8840A emulation. The SCPI instrument control language is 488.2-compliant, and in this mode the instrument returns well-formed IDN strings. The emulation modes are not 488.2 compliant, and return unpredictable results when sent the *IDN? query.

      If your instrument has multiple languages or personalities, and if your application permits, set it to a language that is 488.2-compliant.

    3. If your instrument does not support 488.2, do the following:

      Select the instrument in the My Instruments list. Click the icon. Clear the check box labeled Auto-Identify This Instrument. Click OK. Connection Expert will no longer send *IDN? queries to this instrument. (This option is only available for manually-added instruments.)

  • It may be that you have two instruments listening on the same GPIB address. In this case, when a *IDN? query is sent to that bus address, either instrument or both may respond, and the response received by Connection Expert may be garbled.

    1. Visually scan the list of instruments in Connection Expert's Instruments view. Are there two instruments shown with VISA addresses in an error state (indicated by anything other than a green check mark)? If so, examine both and ensure that they have unique GPIB addresses and that each of their GPIB addresses in Connection Expert corresponds to the GPIB address set on the instrument. (For most instruments you can determine the GPIB address via front-panel menus, or cycle power on the instrument and watch for the address to be displayed during the power-on sequence.)

    2. If only one instrument has a VISA address in an error state, examine all other instruments on the same interface for duplicate or incorrect addresses.

  • It may be that you have added a serial (RS-232) instrument to the wrong port. Some "serial ports" shown by Connection Expert are actually modems mapped to COM ports by Windows. If the IDN response is "*IDN?", this may be a modem echoing the request.

    1. Check the physical connection of your serial instrument and ensure that Connection Expert shows it associated with the COM port to which it is actually connected. Ordinarily, if your PC has two serial ports, they are COM1 and COM2. Higher numbers are often modems or other devices mapped to serial ports.

    2. If the instrument is shown on the wrong port, change it to the correct port.

    Windows on ARM does not support Serial Interface, Serial Instrument, GPIB Interface, GPIB Instrument, Remote GPIB, Remote Serial, and Remote USB