BECKHOFF DK9222-0213-0063 - Manual (Page 3)

XFC
Oversampling
Application Note DK9222-0213-0063
Bit 0
Bit 1
Bit 2
Frame
units
Frame
tens
Second
units
Second
tens
Minute
units
Minute
tens
Hour
units
Hour
tens
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Sync word
(fixed sequence of bits)
Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8 Byte 9 Byte 10
1
2
4
8
x
x
x
x
10
20
x
x
x
x
x
x
1
2
4
8
x
x
x
x
10
20
40
x
x
x
x
x
1
2
4
8
x
x
x
x
10
20
40
x
x
x
x
x
1
2
4
8
x
x
x
x
10
20
x
x
x
x
x
x
binary 0
binary 0
binary 1
binary 1
binary 1
binary 1
binary 1
binary 1
binary 1
binary 1
binary 1
binary 1
binary 1
binary 1
binary 0
binary 1
Table 2 Binary coded time information in the SMPTE frame. Bits containing other information than timecode are marked x.
Analysing a frame
In the following figures two sections of a frame are decoded as an example. Figure 3 shows the complete SMPTE frame, figure
4 focusses on a frame detail (the frame units and the frame tens) to analyse the binary coded time information and transfer it
into the decimal based count of frames.
Frame
Units
User
Bits
Frame
Tens
User
Bits
Second
Units
User
Bits
Second
Tens
User
Bits
Minute
Units
User
Bits
Minute
Tens
User
Bits
Hour
Units
User
Bits
Hour
Tens
User
Bits
SyncWord Frame
Units
User
Bits
Frame
Tens
SyncWord
one SMPTE frame
n+1 n-1 n
64 68 72 76 0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 0 4 8 12
Fig. 3 A single SMPTE sample frame
Bit 0
Bit 1
Bit 2
Bit 3
Frame
units
Frame
tens
1
0 1
2
4
8
1
0
0
1
10
20
x
x
frame units = 9 frame tens = 20
1 0 0 1 0 1 x x
Fig. 4 Bit sequence 1001 | frame unit = 9; bit sequence 01xx | frame tens = 20, as both last bits do not give information about time
To obtain the complete frame value, both values are added: 20 + 9 = 29. It is the 29 th frame in this second. Extracting further
time data out of the complete sample frame shown in fig. 3 results in: 05:38:14:29. Having understood the coding of the frame,
New Automation Technology BECKHOFF 3
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