Single Event Triggering of Multiple TSR PRO/PRO-HB Units

When testing with multiple TSR PRO/PRO-HB units, it is sometimes necessary to trigger recording on all units from the same event.  This article will discuss how to do this and provide connection diagrams.  The User Manual for the TSR unit can be found here.  The following table provides pin out descriptions for the TSR DB15F connector.

TSR Triggering Overview

The TSR unit can trigger in two ways: external event input signal and an internal event trigger.  

Triggering the TSR unit from an external event requires the shorting of pins 4 (+Event input) and 9 (+2.7 VDC) together and shorting pins 14 (-Event input) and 15 (Ground) together.  Doing so allows for current to flow from the +Event input to the -Event input lines.  In order to allow for manual triggering of the TSR unit, a switch must be installed between one of the two shorting connections (pin 4/9 or pin 14/15).  The following figure depicts the method suggested in the TSR User Manual.

Internal event triggering takes place when the trigger threshold(s) configured into the TSR unit at arming have been reached.

Upon receipt of a valid trigger event, the TSR unit issues a trigger confirmation on the -Event output line (pin 13).  

This signal is active while the trigger event is active and is a direct indicator of the receipt of an event trigger (either internal or external) by the TSR unit.  For internal triggering, this signal will be active for only a short amount of time.  For external triggering, the signal will be active for the duration of the switch closure.

Dependent upon hardware configuration, the Status output lines (pins 2 and 12) are active when the TSR unit is recording.  If the unit is in Continuous Recorder mode, this output will always be active and, therefore, is not useful as a means of indicating trigger activity.

Triggering of Multiple TSR PRO/PRO-HB Units from a Single Event

Triggering of multiple TSR units from a single event requires configuring the units as follows:

• -Event input (pin 14) on all units should be shorted together and to Ground (pin 15) on the first unit
• +Event input (pin 4) and -Event output (pin 13) on all units should be shorted together
• +Event output (pin 3) on all units should be shorted together and the +2.7 VDC (pin 9) on the first unit
  • NOTE:  An RC circuit should be placed between the the +2.7 VDC (pin 9) and Ground (pin 15) for circuit protection and power management.  See figure below for values and hookup.

If the units should also accept an external trigger event, the switch trigger should be connected between +2.7 VDC (pin 9) and +Event input (pin 4).

To use an external LED indicator to verify receipt/issuance of a triggering event, see this article.

How it works:

It is important to note that positive and negative (+/-) output signal lines are current-active rather than voltage-active; meaning that the flow of current from the positive line to the the negative line indicates activity rather than the presence of voltage on either/both pins at any given time.

By shorting the signals together as shown above, triggering of all units will occur whenever an external event is seen (+Event input is shorted to +2.7 VDC) and/or an internal event is triggered (current flows from +Event output to -Event output).  In the event of an external trigger, the +2.7 VDC connecting to the +Event input and -Event output pins allows current to flow through the Event input circuitry, causing an external event trigger for the TSR unit.  In the event of an internal trigger, current will flow from the +Event output pin to the -Event output pin of the triggering unit.  Since the -Event output and +Event input pins on all units are tied together, current flowing through the Event output lines of any unit will allow current to flow through the Event input lines on all units.  Thus triggering an external trigger event on all units.