A LeCroy 9400 controlled through GPIB can be returned from remote to local operation without cycling instrument power. Send the IEEE 488 Go To Local (GTL) interface message through the GPIB controller; do not send the RS-232 L command as an instrument data message.
Choose the Correct Local-Control Method
| Control layer | Action | Important constraint |
|---|---|---|
| NI-488.2 high-level API | Call EnableLocal with the board ID and an address list. |
Include the oscilloscope address in the list. |
| VISA | Use VISA GPIB Control REN with mode VI_GPIB_REN_ASSERT_GTL (6). |
This mode sends GTL to the selected device. |
| NI-488.2 interface-level API | Acquire a handle to the GPIB interface, establish controller-in-charge status, and send the command-byte sequence. | Use the board handle, not the oscilloscope device handle, for interface commands. |
Return the Oscilloscope to Local with NI-488.2
- If using interface-level calls, obtain an interface handle for the GPIB board.
- Call
ibsicso the board becomes controller-in-charge. - Call
ibcmdwith the IEEE 488 command bytes shown below. - Verify that the oscilloscope leaves remote mode and accepts its local controls without an on/off restart.
UNT 0x5F
UNL 0x3F
MTAx 0x40 + controller primary address
MLAy 0x20 + oscilloscope primary address
GTL 0x01UNT and UNL remove the current talker and listeners. MTAx addresses the controller as talker, MLAy addresses the oscilloscope as listener, and GTL directs that listening instrument to return to local control. Substitute the configured primary addresses; the evidence does not specify their numeric values.
Use VISA GPIB Control REN
For a VISA implementation, select the GPIB Control REN operation and apply VI_GPIB_REN_ASSERT_GTL (6) to the oscilloscope session. This is the supported evidence-based route for issuing GTL through VISA and avoids manually constructing the interface-message byte sequence.
Distinguish GPIB GTL from the RS-232 Command
The documented RS-232 L command and the GPIB GTL interface message belong to different control paths. When connected through GPIB, use EnableLocal, VISA GPIB Control REN, or the controller-level command sequence. If GTL has no effect, verify that the operation targets the oscilloscope address and, for raw NI-488.2 commands, that the board is controller-in-charge before ibcmd executes.
FAQ
What GPIB command returns a LeCroy 9400 to local mode?
Send the IEEE 488 Go To Local interface message, GTL byte 0x01, while the oscilloscope is addressed as a listener.
How do I send Go To Local with VISA?
Use VISA GPIB Control REN with VI_GPIB_REN_ASSERT_GTL (6) on the oscilloscope session.
Can I send the LeCroy RS-232 L command over GPIB?
No supported evidence establishes that substitution. For GPIB, use the GTL interface message through EnableLocal, VISA GPIB Control REN, or a controller-level ibcmd sequence.
