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OmniPlex® Digital Input GuideFor the Plexon OmniPlex System

OmniPlex® Digital Input Guide

Contents3 Introduction

3 Terminology

3 Hardware Description

4 Pin Diagram

5 Software Components

5 OmniPlex Server

5 PlexControl

6 Common Uses

Documentation History

Date Version Notes Author

April 2013 v1.2 - Minor updates.- Reformatted document to current branding guidelines.

Yolanda Rowe

April 2013 v1.1 - Minor wording changes and additional information on using strobes and RSTART.

William Harman

April 2011 v1.0 - Initial creation of document. Chris Heydrick

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IntroductionThe OmniPlex® Neural Data Acquisition System (OmniPlex) comes equipped with two ports for digital input (DI) that can be set in one of the two modes listed below:

Mode 1: 16 individual events

Mode 3: 15-bit strobed word

The mode terminology is carried over from the Plexon Multichannel Acquisition Processor (MAP) Data Acquisition System. Mode 2 is a mixture of individual events and strobe on the same port and is not implemented in the OmniPlex.

TerminologyHigh-true logic is when the rise from 0V to +5V is counted as true.

Low-true logic is when the fall from +5V to 0V is counted as true.

Note: The transitions from 0V (low) to 5V (high) and 5V to 0V are generally referred to as the rising edge and falling edge, respectively.

An Event is a timestamp that marks the time when an edge is detected.

A Strobed word is a binary number with a timestamp.

RSTART is a special pin that gives the OmniPlex software a signal when it goes high and low. This is useful for controlling the pausing/resuming function in a recording with a single line. When RSTART becomes true, the RSTART signal is detected, and when RSTART becomes false the RSTOP signal is detected.

Hardware DescriptionPorts A and B on the DI board are nearly identical. The exception is that only Port A supports the use of RSTART.

The “Data N” lines represent individual events in Mode 1 and positions in a binary number in Mode 3.

With 15 bits you can send 0 to 32767.

OmniPlex differentiates strobes coming from Ports A and B by adding a sixteenth bit to the strobes coming from Port B. This adds the number 32768 to strobes coming from Port B and the software considers any number over 32768 as originating from there. Some data analysis programs that import .PLX files will not recognize this. For this reason, it is generally best to record strobes from Port A if you only require one port for strobed words.

Digital inputs are detected at a rate of 20MHz but the timestamps only increment every 25µS (40kHz) since the analog data is digitized at that rate. Sending in events faster than 40kHz will result in multiple events with identical timestamps. This is generally not desirable, so throttle your digital inputs accordingly.

5V

0V

Rising Edge

Fallin

g Edge

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The inputs on the digital input board will “fl oat high” (meaning that when disconnected they will be pulled up to +5V). This will not affect the data in single event mode (Mode 1) since events are triggered by edges. Strobed mode (Mode 3) will see those fl oating inputs as “high” (if set to high-true logic), and count them as part of the strobed word. It is standard practice to ground unused lines.

When recording strobes, the voltage setting on the bit pins must be stable for at least 100ns before the strobe pulse is sent to pin 22. Procedures that result in a time less than this, say by splitting a signal into both a bit pin and the strobe pin, will result in the setting to be misrecorded.

Pin Diagram

Pin # Function

1 Data 1

2 Data 2

3 Data 3

4 Data 4

5 Data 5

6 Data 6

7 Data 7

8 Data 8

9 Data 9

10 Data 10

11 Data 11

12 Data 12

13 Data 13

14 Data 14

15 Data 15

16 Data 16

17 Unused

18 Unused

19 Ground

20 +5V

21 Ground

22 Strobe

23 Ground

24 RSTART

25 Ground

26 Unused

In single event mode (Mode 1), pins 1 – 16 are called Data 1 to Data 16. These correspond to events 1 – 16 when input through Port A, and events 17 – 32 when input through Port B.

In strobed word mode (Mode 3) pins 1 – 15 correspond to the fi fteen bits of the strobed word (Data 1 is the least signifi cant bit, and Data 15 is the most signifi cant bit).

RSTART is on Port A ONLY!

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Software ComponentsOmniPlex® ServerSetting the Digital Input (DI) mode and high/true logic is done in OmniPlex Server. Right click on the “Plexon Digital Input” node and select “Edit Device Options”.

The DI device options set the modes and high/low true logic. If the option to select “Edit Device Options” is greyed out (not clickable), then make sure that the data is stopped.

PlexControlEvents can be seen in the activity display in PlexControl as illustrated below.

The activity display illustrated above shows a blue tick mark when a timestamp is recorded. Ticks for waveform crossings and spike unit detection make up the beginning rows (not shown in the above screenshot), while events can be seen by scrolling down to the lower rows. Keyboard events that are activated with the alt + number key include: RSTART, RSTOP, Strobed and some CinePlex®-related events.

Digital inputs are always recorded and there are no enable/disable settings.

About Plexon IncPlexon is a pioneer and leading innovator of custom, high-performance data acquisition, behavior and analysis solutions specifically designed for scientific research. We collaborate with and supply thousands of customers including the most prestigious neuroscience laboratories around the globe driving new frontiers in areas including basic science, brain-machine interfaces (BMI), neurodegenerative diseases, addictive behaviors and neuroprosthetics. Plexon offers integrated solutions for in vivo neurophysiology, optogenetics, and behavioral research – backed by its industry-leading commitment to quality and customer support. For more information, please visit www.plexon.com.

Sales SupportFor Sales Support, email info@plexon.com or call +1 (214) 369-4957.

Technical SupportIf after reviewing this document, you would still like to access Plexon’s Technical Support, we are available via several communication channels. You are invited to reach us through email, on the phone, or even over Skype utilizing instant messaging, voice, and/or video as follows:

EMAIL PHONE INSTANT MESSAGING, VOICE OR VIDEO VIA SKYPE

support@plexon.com 8:30 a.m. to 5:00 p.m. Central Time +1 (214) 369-4957

8:30 a.m. to 5:00 p.m. Central Time Skype name: plexonsupport Skype is a free service. For more information on Skype or to download the application, go to www.skype.com.

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PLEXON®, the five-line symbol, CinePlex®, DigiAmp™, MiniDigi™, Offline Sorter™, OmniPlex®, PlexBright™, PlexDrive™, PlexStim™, Radiant™ and RapidGrid™ are registered and unregistered trademarks of Plexon Inc, Dallas, Texas, USA. ©2013 Plexon Inc. All rights reserved. Other product and company names mentioned are trademarks or registered trademarks of their respective owners.

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Common UsesIndividual event mode (Mode 1) is typically used when there are few actions that need to be recorded. Lever presses or IR beam breaks can be sent into the DI port provided that they produce a detectable voltage edge.

Strobed words (Mode 3) are ideal when there are hundreds or thousands of conditions that need to be recorded as they are happening.

It is possible to rename the events by going to View->Sources and Channels and then clicking on the “Single Bit Events” entry. The Properties view in PlexControl will switch to a spreadsheet of the event names which are editable.

Strobed activity is displayed as a single tick mark in PlexControl but the numeric values are not shown.

The RSTART pin on Port A is typically used to pause and resume a recording. When set to high-true logic, a +5V held on the RSTART line will keep the system paused and a voltage held at 0V will resume the recording (provided that this is set to be the case in PlexControl’s recording options). The RSTART line is different than the other data pins because it has to be held high or low instead of simply provide an edge to detect. PlexControl can be set to start/stop and pause/resume on any event pin, and even specific strobe values. RSTART is intended to be used to start or stop trials, and is not designed to selectively omit data in the middle of an experiment. Though the timestamp is accurate to within 25µs, it takes between 10 and 100ms for an RSTART signal change to initiate procedures in Omniplex® Server. This is also true for other digital input events.