Trigger with Usb-to-serial port cable (rs232) with FTDI chipset

[Julia Shin]

Hi all, 

So I was fishing through all trigger-related questions in this group, but I 
have yet to find a solution that would help me with my problem :( I am also 
a newbie in running trigger so I apologize in advance if my questions look 
really easy... 

So I am trying to run an experiment with a desktop computer that would send 
a trigger signal to another computer telling the other computer to play *a 
sound file* when the signal is sent. Basically the gist of the experiment 
is that we want the other computer to play a sound file which is a mp3 file 
of a metronome (120 bpm) while the main computer sends stimulation to the 
participant and collecting their responses. We can easily do this by 
playing the metronome sound file in mp3 player but we want to control when 
the stimulation would happen in accordance with the metronome sound so I 
think that is why we want to go with the trigger option. 


   - My first questions is: for the receiving end of the computer do I have 
   to have the E-Prime experiment up and running to receive the signal from 
   the main computer?



   - Second question: I used Serial.WriteString SoundOut1.Play (or run) and 
   Serial.ReadString SoundOut1.Play (or run) but E-Prime kept saying Play/Run 
   was not a property of the object. What syntax do I have to use to signal 
   the other computer to play the sound file? And what syntax do I have to use 
   for receiving signal from the main computer to run the sound file when 
   prompted? Is this why my E-prime keeps crashing whenever I tried to run the 
   e-prime experiment for signal receiving computer? I added Serial to 
   Device option in Experiment tab in E-Prime with correct com port and baud 
   rate. Though, is it common to have different com port number for the main 
   computer and the receiving computer? 


So here is the syntax for Serial.WriteString that is placed in InLine that 
is placed in the beginning of the experiment: 


Dim strData As String
strData = "SoundOut1.Play"
Serial.WriteString strData

Then here is the syntax for Serial.ReadString. I just copied this straight 
from the BasicSerial.es sample in PSTNET:

' Just hold the experiment here until some bytes
' arrive over the serial port.
Dim str As String
Dim n As Long

Debug.TimeStampsEnabled = True
Do While Serial.InputCount = 0
Loop

' Read the data that came in
n = Serial.ReadString(str)




   - Third question: Does the trigger syntax for usb-to-serial port cable 
   differ from trigger syntax for serial port? I thought they would be the 
   same but I just want to confirm that there is no problem with the cable 
   here. When I plugged in the cable, both receiving and main computers 
   installed the drivers and I didn't see any warning signs saying that the 
   cables were not working properly. 
   

Sorry that I am asking hundred questions at the same time. But I would 
greatly appreciate your help...I went through the FAQ page relating to 
trigger on PSTNET but they mostly seem to have helpful answers for parallel 
ports. 

Thank you!
Best,
Julia Shin 


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