Executing "TriggerList" using GPIB Interactive Control

Question

Hi all,
For debugging purposes, I am trying to execute a multi-device "TriggerList" command using the "GPIB interactive control" utility.
I have a GPIB-USB-HS unit connected to 2 GPIB devices at addresses 11 and 12. Communication to these devices seperately works fine.
What I tried so far:
(1) Opened NI-MAX, browsed to "Devices and Interfaces" / "GPIB-USB-HS "GPIB0";
(2) Pressed the 'interactive control' button, which opens up the GPIB Interactive Control terminal window, with a "gpib0:" prompt;
(3) Enter "TriggerList 11,12" and press enter.
the result of this is:
[8000] (err)
error: EHDL
count: 0
Using the "NI I/O Trace" tool, I see that a TriggerList(31000, {0x000B, 0x000C}) call is executed, and returns with an EHDL error.
My question: what am I doing wrong, and what do I need to do to execute a successful TriggerList?

Answer 1

Answering my own question:
The trick is to engage 488.2 mode. After that, triggering will work as intended:
    gpib0: set 488.2 0
    488.2 (0): SendIFC
    [0130]   ( cmpl cic atn )
    488.2 (0): TriggerList 11,12
    [0138]   ( cmpl cic atn tacs )
    count:  5
Monitoring the GPIB shows that this sends the 5-byte sequence  0x40, 0x3f, 0x2b, 0x2c, 0x08.