MED Associates SG-231 User manual

instrumentation and software for research
28V DC TO TTL ADAPTER
SG-231
USER’S MANUAL
DOC-203
Rev. 1.5
Copyright ©2019
All Rights Reserved
Med Associates, Inc.
P.O. Box 319
St. Albans, Vermont 05478
Phone: [phone]
Fax: [phone]
www.med-associates.com

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MED ASSOCIATES, INC.
SG-231 28V DC TO TTL ADAPTER
Table of Contents
Chapter 1 | Introduction................................................................................................1
Chapter 2 | Hardware.....................................................................................................2
Configuration 1 .............................................................................................................................. 2
Configuration 2 .............................................................................................................................. 3
TTL Ground And Operate Terminals........................................................................................... 4
Operate LED................................................................................................................................... 4
28V Input Connector..................................................................................................................... 5
Med Input Connector.................................................................................................................... 5
Chapter 3 | TTL Output Setting....................................................................................6
Appendix A | Contact Information...............................................................................7
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MED ASSOCIATES, INC.
SG-231 28V DC TO TTL ADAPTER
Notes
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Diagrams
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Med Associates, Inc.

MED ASSOCIATES, INC.
SG-231 28V DC TO TTL ADAPTER
CHAPTER 1 | INTRODUCTION
The SG-231 is a 28V DC to TTL adapter allows the user to send TTL signals from Med Associates devices
such as response levers, head entry detectors, and nose pokes (Configuration 1).
The SG-231 also allows the user to send TTL signals programmatically, using a Med Associates Interface
and software (Configuration 2).
TTL signals are typically used to synchronize with a third party acquisition interface, operate a TTL
device, or log event markers in a third party physiological data acquisition system.
Figure 1.1 – SG-231 28V DC to TTL Adapter
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Med Associates, Inc.

MED ASSOCIATES, INC.
SG-231 28V DC TO TTL ADAPTER
CHAPTER 2 | HARDWARE
Configuration 1
This configuration allows the user to send TTL signals from a Med Associates device in a standalone or
custom application.
In this configuration the SG-231 requires an input of a 28V DC power source (capable of delivering at
least 1 Amp of current) and a Med Associates device, such as a retractable lever (both sold separately).
See Figure below.
Figure 2.1 – SG-231 Configuration 1
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Med Associates, Inc.

MED ASSOCIATES, INC.
SG-231 28V DC TO TTL ADAPTER
Configuration 2
This configuration allows the user to convert the 28V DC signal from an output on a powered Med
Associates Connection Panel to a TTL signal.
The SG-231 does not require a 28V DC input in this configuration; the output on the powered
Connection Panel supplies 28V DC. See Figure below.
Figure 2.2 – SG-231 Configuration 2
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Med Associates, Inc.

MED ASSOCIATES, INC.
SG-231 28V DC TO TTL ADAPTER
TTL Ground And Operate Terminals
TTL Output Screw Terminal: Connect the TTL Output screw terminal to the TTL input device
TTL Ground: Connect to the TTL input device’s ground.
NOTE: Do not connect the TTL Ground connection to the 28V power supply ground. These grounds
must remain isolated.
The optional Med Associates PHM-155G screw terminal to BNC cable makes for convenient connections
to most TTL devices.
Figure 2-3 - TTL Ground and Output Screw Terminals
Operate LED
The Operate LED indicator, Figure 2-4, will illuminate when the unit receives an input signal to operate
the TTL device.
Figure 2-4 - Operate LED Indicator
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MED ASSOCIATES, INC.
SG-231 28V DC TO TTL ADAPTER
28V Input Connector
•Configuration 1 - The 28V INPUT connector is connected to a 28V DC power supply that is
capable of providing at least 1 Amp of current (e.g. SG-501).
•Configuration 2 - The 28V INPUT is not required.
Figure 2-5 - 28V Input Connector
Med Input Connector
•Configuration 1 - The INPUT connector is connected to the output of a Med Associates lever,
head entry detector, nose poke device, etc.
•Configuration 2 - The INPUT connector is connected directly to an available output on a
powered Med Associates Connection Panel.
Figure 2-6 - Input Connector
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MED ASSOCIATES, INC.
SG-231 28V DC TO TTL ADAPTER
CHAPTER 3 | TTL OUTPUT SETTING
The SG-231’s TTL logic jumper is factory set to the Active Low (connecting pins 1 and 2).
In the Active Low position the TTL signal will be HIGH (~5V) when OFF and LOW (~0V) when operated.
To change the TTL logic jumper to the Active High (connecting pins 2 and 3), remove the 2 screws from
the bottom of the SG-231 and lift the top cover off. Near the center of the printed circuit board is
jumper location JP1, see Figure 3-1.
Figure 3-1 – TTL Logic Jumper
Remove the jumper and reposition it to cover pins 2 and 3 as shown in Figure 3-2.
In the Active High position the TTL signal will be LOW (~0V) when OFF and HIGH (~5V) when operated.
Figure 3-2 - Active High Jumper Setting
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Med Associates, Inc.

MED ASSOCIATES, INC.
SG-231 28V DC TO TTL ADAPTER
APPENDIX A | CONTACT INFORMATION
Please contact Med Associates, Inc. for information regarding any of our products.
For Technical questions, email [e-mail].
For Sales questions, email [e-mail].
Visit our website at www.med-associates.com.
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Med Associates, Inc.