Recently some customers may have seen a Perception PVR, digital video
recorder being used on the Mark Roberts Motion Control stand at IBC'98.
This has proved to be a very useful device and some questions were
raised about the interface. Although the Perception has the facility to
run a Sony BVW-75 VTR RS422 protocol, this was not used and a much
simpler and cost effective interface was adopted using simple output
triggers from Flair. One trigger was used to start the Perception and
another to stop it.
The wiring is very simple. Pin 4 of the serial port of the PC containing
Perception is the supply which should be wired to the positive side of
both of the Rootbox outputs being used. Then one negative output is
taken to pin 6 (DSR) and the other to pin 8 (CTS). One has to realise
the following though, Perception inputs are active low, meaning that
when the outputs switch off the trigger is activated. To record 100
frames starting at frame 0, one has to have the start output come on
frame -1 and go off at frame 0, while the stop output has to come on at
frame -1 (if it is not on the Perception will start when a start pulse
arrives and then immediately switch off) and then go off on frame 100.

Flair is equiped with a series of inputs and outputs, capable of
interfacing to external devices. There are basically 4 inputs, one of
which is normally dedicated for synchronizing to an external camera, and
11 outputs, one of which is normally dedicated for controlling an
external camera.
These inputs and outputs are optically isolated and have fairly large
resistors in series (1.0K to 2.2K) therefore only allowing a small
current to flow. To control devices that require a higher current than a
few milliamps, requires either an external transistor or a transistor
and a relay.