Instrument Discovery and Identification on Specific Interface Types
Select an interface to understand how Instrument Discovery works for that interface type.
GPIB (including PCI GPIB, USB/GPIBOn startup, the Discovery Service makes a request to the test system controller to sequentially address each primary and secondary address on the GPIB bus. The service determines that there is an instrument at each new address where there is a responding device.
Subsequently, GPIB discovery is run whenever the interface is scanned, but instruments on Keysight GPIB interfaces are only addressed if the Discovery Service determines that the instrument's state has changed. (Other vendors' instruments are addressed each time discovery runs, as the service has less information about their state.)
The Discovery Service sends a *IDN? query to each GPIB instrument when it is first discovered, unless there is an open session to that instrument already. If you manually add a GPIB instrument, you can choose whether it will be auto-identified (with *IDN?) or not.
You can choose to turn off auto-scan and auto-discovery for Keysight GPIB interfaces.
You can manually add GPIB instruments that have not been auto-discovered. If you manually add a GPIB instrument, you can choose to turn off auto-identification for that instrument.
See About Instrument Discovery and Identification for more information.
Automatic Disabling of GPIB Auto-Scan
The GPIB auto-scan feature scans the interface in a way that is designed to avoid putting instruments into remote mode (i.e., disabling front panel control). However, some instruments (for example, some Keysight 34410As and 34980As) do go into remote mode when scanned in this manner. When the Discovery Service detects an affected instrument model, it turns off auto-scan for the affected GPIB interface.
This may occur with various instruments; whether you are affected by this issue may depend on the version of firmware on your instrument. For up-to-date information about compatibility issues and solutions, including a list of affected instruments, visit www.keysight.com/find/iosuitecompatibility.
If you see an instrument going into remote mode periodically (e.g., every 15 seconds), or you see some other instrument problem recurring periodically in a similar way, and the auto-scan is not disabled by the Discovery Service, you can try to prevent the problem by manually turning off auto-scan. To do this, select the GPIB interface in the Instruments list, click the Edit button, then select the Do Not Auto-Scan for Instruments on this Interface option. In the edit dialog, you can conversely choose Always Auto-Scan for Instruments on this Interface (overriding the automatic disabling in case of problems).
USB
The Windows Plug&Play Manager keeps track of all USB devices that are attached to the PC, and provides a list of connected devices to Connection Expert. When Connection Expert notices a new USB device, it considers this device to be newly-discovered.
The IO Libraries Suite supports the connection of USB-TMC instruments only.
LAN
The Discovery Service automatically discovers many LAN instruments on the same subnet as the PC on which the service is running. Auto-discovered LAN instruments will be added to the TCPIP0 interface. However, they are not automatically added to the Connection Expert Instrument view list. Some older instruments do not announce themselves via the mDNS protocol, and therefore they are not auto-discovered.
LAN instruments not automatically discovered must be added manually. See Add a LAN Instrument for instructions
- To manually add LAN instruments outside of the local subnet: Click
, select LAN Instrument from the context list. This opens the list of discovered LAN instruments. Click the Enter Address tab; enter the LAN address or hostname, select the protocol used to communicate with the instrument. Click OK. See Add a LAN Instrument for instructions. - To add LAN instruments to the instrument list, click Add, select LAN Instrument from the context list. This opens the list of discovered LAN instruments. Click the check box for each instrument you want to add to the list. Click OK.
Many instruments on your local LAN subnet are discovered automatically when they announce themselves via the mDNS protocol. Some older instruments do not announce themselves, and therefore they are not auto-discovered.
- Instruments on your local subnet which conform to the LXI standard, version 1.3 or later, are discovered automatically. If they go offline they will appear in the Instruments list as unavailable (with a
icon)
- Instruments on your local subnet which conform to the LXI standard, version 1.2, are discovered on PC startup and when you click Rescan All
in Instruments view. If they go offline, they will appear available until you click Rescan All
A manually-added LAN instrument is identified using its LXI Identification XML if it implements the LXI 1.2 (or higher) standard. If not, it is identified using a *IDN? query, which is sent when the Test This VISA Address button is clicked in the Add a LAN Instrument or Edit LAN Instruments view.
- You can prevent *IDN? queries from being sent to a particular instrument by clearing (unchecking) the Allow *IDN Query check box in the Add a LAN Instrument or Edit LAN Instruments view for that instrument.
- If you do this, and the instrument does not provide mDNS identification, the instrument address will be shown as unidentified (with a