About Instrument Discovery and Identification

The Keysight Instrument Discovery Service discovers and identifies interfaces and instruments connected to your PC and on the local subnet of your local area network (LAN). The Discovery Service also identifies newly-discovered instruments.

This means that in most cases, you do not have to manually add or configure instruments in Instruments view. The advanced information in this section is provided to give you background on the discovery and identification process.

Here are some key terms in this discussion:

Scan: Scanning is a process by which the Discovery Service checks for new instruments on I/O interfaces. The Discovery Service always does a scan on startup and whenever you click Rescan All ( in Windows, in Linux) . Auto-scanning is the process by which the Discovery Service periodically scans in the background.
Auto-discovery: Auto-discovery is the process by which each interface (GPIB, USB, LAN, etc.) is scanned to determine whether there are instruments connected to it, and reports that information back to the Discovery Service.
Auto-identification: Auto-identification is the process by which the Discovery Service asks each discovered instrument to report its identity, usually but not always by means of a *IDN? query.

You can turn auto-discovery either on or off and, in many cases, auto-scan for GPIB interfaces, on a per-interface basis. For other interfaces, those processes depend on the type of interface; see Instrument Discovery and Identification on Specific Interface Types. You can turn auto-identification on or off for individual instruments on some interface types. See Editing Existing Instruments and Interfaces for specific settings available on each type of interface and instrument.

About Auto-discovery

How Does Auto-discovery Work?

The Discovery Service runs automatically when your PC starts up. When the Discovery Service is running, it periodically requests certain interfaces (such as GPIB) to do auto-discovery; instruments on other interfaces, such as USB and PXI, are discovered via mechanisms specific to that interface. In one way or another, each interface automatically detects any new instrument that has been added (see exceptions below).

When the Discovery Service discovers a new interface or instrument, it attempts to identify the new instrument or any instrument(s) connected to a new interface. When discovering a remote device, the service typically does not send information to or receive information from the remote device. This makes the discovery of a shared device a safe operation; since there is no data exchange, there is no risk of interfering with another user's work.

The Discovery Service can find most instruments that are connected to your LAN local subnet. LAN instruments on the local subnet are not automatically listed in the My Instruments list. To add a LAN instrument to the My instruments list:

See if the instrument is listed in the Add a LAN Device window. Select the LAN interface, click , then LAN Instrument. If the instrument(s) you want are listed in the Add a LAN Device list, click the check box for the instrument(s) then click OK.

If the instrument is not listed, click the Rescan All ( in Windows, in Linux) button in Instruments View and wait for the rescan to complete. This may cause the instrument to be added to the list.

If the instrument is still not listed, add the instrument manually. Click the Add button, LAN Instrument, then select the Manually Enter Address tab. Fill out the form to add the instrument. At this time, you can choose whether to allow *IDN? queries to be sent to the instrument to assist in identification. Instruments that must be manually added are typically older instruments, or are located beyond your local subnet.

The Discovery Service can also find instruments that are connected to LAN via a remote I/O server or a GPIB/LAN gateway such as the Keysight E5810. See Remote IO Server Software Overview for more information.

Exceptions to Auto-discovery:

If you want to add a LAN instrument that is outside of your local subnet, or any instrument that was not auto-discovered and not discovered on rescan, you must manually add the device to your I/O configuration.
To add an instrument that resides outside of your LAN local subnet, click the Add button, LAN Instrument, then select the Enter Address tab. Enter a hostname or IP address in the address field and select a protocol. At this time, you can choose whether to allow *IDN? queries to be sent to the instrument to assist in identification. Instruments that must be manually added are typically older instruments, or are located beyond your local subnet. You can also test the VISA address to make certain it is a valid address and identify the instrument. Click OK to add the instrument to the My instruments list.

If you want to add a remote interface (a gateway or a PC running Remote IO Server software) or an instrument that is connected through a remote interface, you must manually add the device to your I/O configuration.
To add a remote GPIB or USB interface, click Add, then select the type of interface you want to add . Fill out the form to add the interface. Instruments that must be manually added are typically older instruments, or are located beyond your local subnet. Select the remote interface type (remote GPIB or remote USB), and then specify the IP address or hostname of the remote I/O server or gateway or use the Find Interfaces button to locate it.
To add a remote serial instrument, click Add, then select the type of instrument or interface you want to add. For example, select Serial instrument on ASRL1, and then specify the connection address and properties as necessary.
Disable the firewall for the working of Find Interfaces functionality on Linux systems.

The Discovery Service cannot discover serial instruments (those connected to your PC's COM ports). You must add them manually.
To add a serial instrument, click Add, select Serial instrument on ASRL1. Enter the properties of the serial connection (baud rate, etc.).

You can turn off auto-discovery for most GPIB interfaces, including USB/GPIB, remote GPIB, and PCI GPIB interfaces. If auto-discovery is turned off for an interface, no instrument will be found on that interface.
To turn auto-discovery on or off, select the interface of interest, then (Windows) / (Linux). Set or clear the check box labeled Auto-Discover Instruments Connected to This Interface.

On PCI GPIB and USB/GPIB interfaces, by default, auto-scan is enabled unless the Discovery Service detects an instrument or condition that may cause problems on auto-scan. For example, certain instruments go in remote mode when scanned, so if one of those instruments is detected, auto-scan is disabled on the corresponding interface. You can choose to have auto-scan always on (disregarding the potential problem conditions) or always off. If auto-scan is turned off for an interface, either by your choice or because a problem was detected, then instruments will be found on that interface only when you start up your PC and when you click Rescan All.
To override the default and have auto-scan always on or always off, select the interface of interest, then Edit. Choose the appropriate option.
Auto-scan is not supported for 488.2 GPIB interfaces and remote GPIB interfaces.

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

Auto-discovery for Specific Interface Types

For a list of how auto-discovery works for instruments connected to specific interface types, see Instrument Discovery and Identification on Specific Interface Types.

About Auto-Scan

How Does Auto-Scan Work?

The Discovery Service runs automatically when your PC starts up. Whenever the Discovery Service is running, it scans the buses on your PC to look for new interfaces or instruments. The service automatically detects any new interface that has been added locally to your test system, and it polls all interfaces that have auto-scan enabled (whether newly found or pre-existing), requesting them to auto-discover their instruments.

Auto-Scan for Specific Interface Types

For a list of how auto-scan works for each type of interface, see Instrument Discovery and Identification on Specific Interface Types.

The IO Libraries Suite auto-scan feature can cause certain instruments on GPIB interfaces to go into remote mode every 15 seconds. When the Discovery Service detects an affected instrument model, it automatically turns off auto-scan for the affected GPIB interface. For detailed information on this issue, see Instrument Discovery and Identification on Specific Interface Types.

In addition, some older instruments do not respond correctly to the SCPI identification query, *IDN? These instruments may experience problems when queried by the IO Libraries Suite. After two failures, IO Libraries Suite will stop sending *IDN? to that instrument until the next reboot or reconnect. You can prevent *IDN? from ever being sent to an instrument by manually adding the instrument and turning off its auto-identification property.

About Auto-Identification

How Does Auto-Identification Work?

For manually-added GPIB, LAN, and serial (RS-232) instruments, you can choose to allow the Discovery Service to send a *IDN? query to determine the instrument’s identity. *IDN? is the standard identification query understood by all devices that implement the IEEE 488.2 command language. The instrument responds with a string containing information about its manufacturer, model, serial number and firmware revision.

If auto-identification is enabled, the Discovery Service may send an identification request to:

A new instrument after it has been detected.

An instrument that has changed state since the Discovery Service last scanned the interface, and that is not currently in use.

Identification requests are sent only when necessary, to avoid disturbing other programs or users of the instrument.

Why Would You Turn Off Auto-Identification?

The *IDN? query is defined by the IEEE 488.2 standard. Since most instruments manufactured in recent years are compliant with IEEE 488.2, the majority of instruments will correctly respond to an *IDN? query. However, some older instruments may not respond correctly or may not respond at all. IO Libraries Suite will stop sending *IDN? to a particular instrument after that instrument has failed twice to respond, but if the PC is rebooted or that instrument is reconnected, *IDN? will be sent again. Therefore, if a particular instrument has consistent trouble responding to the *IDN? query, you may want to turn off the auto-identification feature for this instrument.

You may be using a shared instrument — that is, an instrument used on more than PC. In this case, all users may wish to turn off the auto-identification feature for that instrument if they wish to avoid disturbing one another's test processes; however, since IO Libraries Suite sends *IDN? only when necessary and when the instrument is not otherwise in use, this may not be necessary.

In a few cases, you may experience very slow response of a remote instrument due to networking issues. If this happens, you may choose to turn auto-identification off for that instrument. You can manually send *IDN? to any instrument at any time by using the Interactive IO utility.

How Do You Turn Auto-Identification On or Off?

You can turn auto-identification on or off for manually-added GPIB, LAN, and serial (RS-232) instruments. To turn off auto-identification for a particular instrument, select the instrument from the My Instruments list, then Edit. You will see the properties for that instrument in the configuration pane on the right. Clear the check box to turn the auto-identify property off, then select OK.

You cannot turn auto-identification off for auto-discovered instruments. If you have an auto-discovered instrument that should not receive *IDN? queries, remove the instrument from the My Instruments list and manually re-add that instrument and turn off its auto-identify property.

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