BECKHOFF DK9222-0213-0063 - Manual

XFC
Oversampling
Application Note DK9222-0213-0063
Keywords
SMPTE
timecode
EL3702
entertainment
stage
show
light
technology
light control
decoding
time information
synchronising
LED
Reading SMPTE timecode information
This application example provides basics on the SMPTE timecode and contains a TwinCAT sample code for
extracting the time information sent by a SMPTE master. Using an EL3702 EtherCAT oversampling terminal
it is possible to “listen” to the analog signal the SMPTE master broadcasts to the slaves. For the sample
code see DK9222-0213-0063_TwinCAT_sample.zip.
Preamble
Please keep in mind that in this document the term frame is used in a double meaning:
– Part or unit of a protocol.
– Snippet or single picture as unit of a movie.
What is SMPTE-Timecode?
Defined by the Society of Motion Picture and Television Engineers, the SMPTE timecode is a standard to provide an absolute
time reference for media metadata. Mainly it is used to synchronise different layers in media productions. A SMPTE frame
consists of 80 bits and is always broadcast from a SMPTE master to the slaves. Via an analog signal (±1…10 V), the SMPTE
timecode provides time information in a binary coded decimal identification on an absolute 24-hour time base (hh:mm:ss:ff).
Depending on the signal coding, there are different rates of frames per second (fps); the most common values are 24, 25, and
30 fps.
Broadcast
Audio
hh:mm:ss:ff
Video
hh:mm:ss:ff
Automation
hh:mm:ss:ff
Other
hh:mm:ss:ff
SMPTE master
hh:mm:ss:ff
Fig. 1 SMPTE timecode: Broadcasting an absolute time reference to the slaves
New Automation Technology BECKHOFF 1
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