Stumbling Toward 'Awesomeness'

A Technical Art Blog

Sunday, June 15, 2008

Building a J1 Remote Trigger for Vicon Datastations

Remote Trigger? Why Would I Want That?

Vicon Datastations allow you to string off a remote trigger which can allow you to start and stop of a motion capture take with a physical button. This could allow you to start/stop motion capture with sensors or anything else. In our case, we wanted to start/stop another device at the same exact time and have it sync’d with the mocap data, also, allow one person to run the device and the mocap session.

Disclaimer: I am aware that the remote interface is the same for the V8i/612/624/460/V6 Datastations, but I built this for the V8i, which looks like this:

This is what the ‘J1 REMOTE‘ port looks like on the back of your Datastation:


Here is the description of the J1 Remote in the Vicon hardware manual:

Located directly below the camera inter face connectors, the J1 connector function is to allow the remote control of data capture from external switches or photoelectric sensors. Connecting Start (pin 3) or Stop (pin 5) to Ground (pin 7) will initiate the selected function.  Pin 1 generates a negative going TTL gated reference signal, which is aligned, to the camera Horizontal Synchronisation (HD) signal and present when data capture is being per formed.

The hardware manual will tell you that the J1 Remote Interface Connector is a Lemo Part (FGG.1B.307.CLAD52). So you will have to order this (follow the link). Below is the pin out from the manual, it’s pretty simple stuff:

Building the Trigger

Working with Relays

So, what we want to do is make a start and a stop button, or you could make an on/off switch. I made a button. The button flips a relay, which is like a switch. Below you see 5 pins, labeled ‘start‘, ‘stop‘, ‘grnd‘ and ‘coil‘. When you apply power to the coil, it will connect the grnd from stop to start and vice versa. Because it’s a magnet that flips the switch, nothing from the inner circuitry of the trigger can send any interference to the Vicon Datastation.

Below you see two relays, one triggers start/stop, the other triggers an LED. You can get relays that flip multiple poles at once. If you wanted to start/stop other devices with the same buttons you would add more relays, or use a multi-pole. In my example below I was sure to get relays and LEDs that work with a 9v battery, this way you do not need resistors or anything to alter the voltage.

The Altogether

This is what a final remote trigger can look like, green starts, red stops. The green LED can be on while capturing. The above relay will flip the light on/off based on button contact, even if red is pressed first, so you may want to go a different route if someone has butter fingers. The cord is durable microphone cord, as we only need 3 wires (start/stop/grnd, mic cable =  left/right/grnd).

Note: The J1 Remote Trigger works in Vicon Workstation, however, when Vicon updated it’s software to IQ, they did not want to spend the time to continue support of the remote trigger. IQ supports newer technology like the ‘MX Remote’ made by Vicon, which they would rather have you purchase. So yes, if you update your Vicon Software, certain features of your Vicon hardware will become useless.

posted by Chris at 1:50 AM  

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