E-Prime 3.0 does not recognize scanner triggers from Lumina 3G controller

[wtwang]

Dear all,

We have an issue for E-Prime 3.0 to detect/recognize scanner triggers via Lumina 3G controller.

The Lumina (firmware 2.2.2) is connected to a 3T GE Signa PET/MR scanner and to a PC installed with E-Prime 3.0. The scanner sends a trigger for each slice. To check the detection of scanner triggers, we had one slice and TR=3s so that there is one scanner trigger every 3s. The Lumina is set to Standard, E-Prime, and 19200/9600 (we checked both). The trigger light on the Lumina controller turns on/off fast during the shimming/calibration prescan. During the fMRI scan, the trigger light turned on once every TR (=3s). The problem is that E-Prime did not recognize what Lumina sent when detecting the scanner triggers, and the E-Prime stimulus presentation stayed at the prompt “Waiting scanner trigger …”.

So, we installed Xidon2 and tried the setting listed in

Scanner trigger problem

Dear all, We recently got a Lumina 3G+ controller to use in an fMRI study, but we are having problems to receive the scanner triggers. The Lumina is connected to a 3T Siemens MRI scanner and to a MacBook Pro (macOS Big Sur, 11.5.1), and is set to Keyboard mode using ASCII (firmware 2.2.8). The problem is that sometimes the trigger is received and sometimes not. This seems completely random, and in any case the trigger light (on Lumina) never turns on. We tried a Lumina controller from other res…

We noticed that whenever Xidon 2 is connected to Lumina, it changed the Lumina setting from E-Prime to SuperLab. After finished changing the setting, we switched back to E-Prime from SuperLab, and started E-Prime and the fMRI scan. The results were the same: E-Prime does not recognize scanner triggers.

We then installed Realterm (2.0.0.70) to check what Lumina 3G sends to the PC with E-Prime. Baud rate on Realterm was set to match that on Lumina. After selecting each option in the list under “Display As” one by one, we saw sets of multiple 0s or symbols (depending on which “Display As” option we chose). In addition, these sets of 0s/symbols kept appearing on Realterm, even though there was one scanner trigger every 3s. That is, Lumina controller kept sending streams of 0s/signals to the PC with E-Prime, although Lumina trigger light turned on once every 3s.

Did we miss any steps in the setup of Lumina? Or are there better ways to decipher what Lumina sends to the PC with E-Prime 3.0?

Any suggestion would be appreciated. Thanks.

Wen-Tung

[Hisham]

The fact that the Lumina Trigger light is turning on when you expect it to is a good sign.

It is normal for Xidon to switch the protocol from E-Prime (or any other setting) to SuperLab. That’s because it’s the only mode that allows Xidon to make changes to the controller settings if you want to.

When you set the protocol back to E-Prime, the controller will start generating 800 bytes per second regardless of whether a key is pressed or not. This is because the controller is trying to emulate PST’s own Serial Response Box (SRB Model 200). These bytes will be all zeroes unless a key is pressed or a scanner trigger is detected, in which case a specific bit will be enabled that corresponds to the key or the trigger.

The only explanation I can think of is that E-Prime is not interpreting the scanner trigger bit. You would need to adjust your E-Basic code for that. A different approach is to set the controller to Keyboard mode instead. This mode is easier to work with; you can see the output in any text editor and it’s easier to code for in E-Prime.