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Interface with visual presentation programs

MP Systems can interface with most of the major visual presentation packages by using the STP100C module. The STP100C module provides an optically isolated connection between the computer that is running the visual presentation program and the MP System. The STP100C module has two interface cable options, one for a digital I/O card (DB37 connector) and the other for a Parallel port (DB25 connector). SuperLab is typically used with a digital I/O card. E-Prime®, DirectRT®, MediaLab®, Inquisit®, and Presentation® can output timing marks via the Parallel port. Note that parallel ports are no longer standard built-in components of new computers. USB to parallel port adapters will probably NOT work as substitutes. See the E-Prime Knowledge Base for more on this subject.

BIOPAC has performed tests using E-Prime with a USB to TTL module that performs as well as a parallel port; the device appears as a serial port to the host computer, so presentation programs must be able to control a serial port to make use of the device.


  SuperLab Setup

If you already have SuperLab and the Digital I/O card with the Support Pack, use the STP100C optical interface to connect to the MP System. SuperLab uses Port A on the digital I/O card for input and Port B for output (Port C is not used).

    1. Connect the STP100C to the left side of the UIM100C module.
    2. Use the DB37 ribbon cable, CBL110A, to connect the STP100C module (computer I/O 37-pin connection) to the 37-pin connector on the digital I/O card in the computer.

The ribbon cable makes the following connections:

Be sure to reference the appropriate digital outputs from the SuperLab PC to the MP unit when you create your presentation.

Set up digital channels 8-15 (as used in your presentation) via — in most AcqKnowledge versions — “MP150 > Set Up Channels…”; select the Digital Channels via radio button or tab (depending on which version of AcqKnowledge you are using). In version 4.4, the menu choice is “MP150 > Set Up Data Acquisition…”, “Channels” should be selected in the pane on the left, and “Digital” should be selected from a tab. SuperLab stimulus output channel 1 corresponds to MP digital channel D8.

To record responses and use the stimulus presentation times for analysis purposes, you must set the appropriate channel(s) to “Acquire” data.

For debugging purposes, pins 19 and 21 are GND on the STP100C DB37 connector.

See also: StimTracker Connections for BIOPAC STP100C (MP150 or MP100 Systems)

  Printer Port Setup: E-Prime, DirectRT, MediaLab
    1. Connect the STP100C to the left side of the UIM100C module.
    2. Use the DB25 ribbon cable, CBL110C, to connect the STP100C module (computer I/O 25 pin connection) to the DB25 female printer port on the computer.

The ribbon cable makes the following connections:

For debugging purposes, pins 18 and 25 are GND on the STP100C DB25 connector.

In most versions of AcqKnowledge, go to “MP150 > Set Up Channels” and click on the Digital tab (or radio button depending on what version of AcqKnowledge you are using) to generate the digital channels dialog. In version 4.4, the menu choice is “MP150 > Set Up Data Acquisition…”,  “Channels” should be selected in the pane on the left, and the digital channels are selected via a tab. To activate digital input channels, choose channels 8 – 15 in whatever combination you wish to receive your visual presentation pulse signals.


  Desktop computer

If the stimulus computer is a desktop, then the parallel port is used to connect the STP35A cable between the computer and the MP36/35. Note, do NOT use a CBL110C or any other straight-through cable in place of the STP35A as such cables will not make the proper connections.

In the BSL software, enable the digital channels that are receiving the pulses from the visual presentation computer. To do this, go to “MP35/36 > Set Up Channels…”, and then enable “Acquire” and (optionally) “Plot” in the Digital input channels section.


If your computer is a laptop, then you will need a card as recommended by the makers of the visual presentation software.

For example:

E-Prime – see Using E-Prime (Psychology Software Tools) with BIOPAC

SuperLab – see StimTracker Interface to BIOPAC MP36 or MP35

MediaLab – see Media Lab (Empirisoft) Support

Any questions about programming these third-party visual presentation programs should be directed to the software maker’s support group.

Note: Matlab users – see  this link for Windows, and this link for Mac, but beware that some information there may be out of date. See discussions in the Psychophysics Toolbox mailing list, particularly for descriptions of difficulty with communication with Measurement Computing Daqs with newer (post 10.6) versions of Mac OS.

Troubleshooting: Note that MP systems passively listen to the digital channels when configured to acquire. If a signal is not registered in AcqKnowledge (or BIOPAC Student Labs), it is almost always because there is a problem with the system sending (or more appropriately, not sending) the signals. That said, here are some things to look for on the BIOPAC side of this communication:

  1. Is the correct cable being used?
  2. Is the data acquisition rate fast enough?  If very brief pulses are sent, it is possible these pulses will arrive between times that the MP system scans the hardware, so increasing the sample rate may allow detection of pulses otherwise missed.
  3. Are the appropriate channels configured for acquisition?  Which channels will carry the signal is established by the signals sent by the stimulus presentation computer. For debugging purposes, it may be best to acquire and plot ALL of the digital channels in the MP system during testing.
  4. Is more than one source trying to use the digital channels?  On the STP100C, the DB37 and DB25 connectors are alternatives. Do NOT attempt to use both connections at the same time. Similarly, the digital channels may be accessed via screw terminals on the back of the UIM100C. Do not try to drive the digital channels through these screw terminals while also trying to drive them via an STP100C.

When nothing is connected to digital channels 8-15, they should all be in the high (5 volt) state. A basic test of communication is to configure the stimulus presentation software to set and hold all eight channels to the low (0 volt) state such as by writing zero to the parallel port when using that mode of communication, and verify that they all drop.

See also: How do I sync my stimulus presentation software with my data acquisition software? Knowledge Base Article.

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