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Ole Jakobsen
October 13, 2003, 10:57:25
Hello,

I'm going to trigger my DFW-SX900 camera using a signal from my computers parallel port. What I'm thinking of doing is simply connecting the GND (ground) pin and one of the data outpit pins (D0-D7) to the camera's TRIG IN connector (GND and TRIG IN pins).

Is it necessary for me to provide any kind of protection circuit (like an opto coupler) on the parallel cable to prevent my camera and/or computer from being damaged?

Regards,

Ole Jakobsen

Stefan Geissler
October 13, 2003, 14:55:24
Ole,

I am not sure, that it is possible to connect the Sony external trigger to the LPT, because the parallel interface has no TLL. In this case, it is more suitable, not using the external trigger and snap an image with a timer or other event from the live video.

Ole Jakobsen
October 13, 2003, 15:20:33
Hello,

I really need to use the device trigger function of the camera, because of some very strict precision requirements to the pictures grabbed.

I think the LPT is capable of maintaning proper TTL levels. Do you see any security riscs (hazards to the computer and/or camera) in connecting the camera's TRIG IN connector directly to the parallel port - and if so what can be done about it?

How do you recommend controlling a device trigger from the computer?

Regards,
Ole Jakobsen

Stefan Geissler
October 14, 2003, 08:28:02
Ole,

Thank you, that you have translated my error (“TLL”) correctly to “TTL”. I am no electronics engineer, so i am not able to give you hints, that will not possibly damage your computer.
You should consider, that you will have a delay in the parallel port. Therefore, the difference between using the external trigger and snapping a frame from the live video stream would not be as big.
If i would need to control the external trigger from the PC's ports, i would use the serial or the USB port. Especially for the USB port you can purchase many solutions, that will do what you want without any risk to your PC's hardware. For examples, search for the internet for “USB controlled trigger”. Most of these controllers come with a simple to use programming interface for Visual Basic or Visual C++.

If your trigger signal comes from external source, it would be the better and more precise way to send the trigger signal directly to the camera. The PC needs some milliseconds to process the signal through the ports.