biopac unresponsive to ttl signals from matlab

I am currently using a Biopac MP150 model in our lab.

I have been trying to send TTL Signals via matlab to the biopac equipment via parallel port of address 378. The matlab codes seem to be fine, however, the biopac doesnt seem to respond to the ttl signal.

What I have done till now:

As for matlab, i have downloaded and installed lptwrite.m which is the required software to send ttl signals. and, i have created a plot via AcqKnowledge software to view the signals obtained/responsive by biopac.

On the plot, when the PC is on, its on high(5V) constantly. However, when the command: lptwrite(888, 0), is applied to make it low(0V). It still stays on high(5V) when it should become low(0V).

Apparently, I was using biopac to collect GSR data on a participant simultaneously. The plots for the ttl signal and gsr were on the same screen and run live at the same time. The GSR data was running fine while the ttl signal was consistent and unresponsive at 5V while the signals to alter the ttl codes were executed.

The matlab codes used are shown below:

lptwrite(888, 0);    % to transmit a 0V signal, 888 is the address for 378 in decimal
WaitSecs(0.005); % waits for 5 milli seconds
lptwrite(888, 255); % to transmit a 5V signal

Ultimately, I would like to make biopac responsive to the matlab codes below so that it shows on the plot as per the codes mentioned above via AcqKnowledge Software.

The aim is to use ttl signals as a markers for paradigms.

Is there anyway that I could make this happen?

Thanks

Answer 1

[Walter Roberson]

Are you trying to use 32 bit Windows or 64 bit Windows ? lptwrite() is only for 32 bit Windows.

http://psychtoolbox.org/wikka.php?wakka=FaqTTLTrigger

[Walter Roberson]

Were you able to do any debugging with a utility such as http://retired.beyondlogic.org/pardebug/pdebug.htm ?

Answer 2

[Ramanan]

Hi Walter,

well, i have to let you know i have found another toolbox and it is working perfectly now. I didnt manage to debug the parallel port. Though, this toolbox is good enough for me now. Thanks Walter. Really appreciate the info and aid.

Very much Thanks Warmest Regards Prasad

[Hakan]

Hi Ramanan,

Can you tell me which toolbox you used? How did you overcome the problem exactly?

Thanks in advance,

Hakan

Answer 3

[Ramanan]

Well, its 32 bit windows xp with 32 bit matlab, and i've followed the exact procedure of that website. Any matlab codes that you know that would make the biopac machine responsive?

Thanks Walter:)

Answer 4

[Laura]

Dear Prasad, could you tell me which toolbox you finally used? I might be facing the same problem ;) Best, Laura