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Model 8010TM SDI Time Code Master Manual
STX
Start of message character (02 hex)
BYTE COUNT
Count of command message not including the STX, BYTE COUNT or CHECKSUM.
MESSAGE
Variable length command message.
CHECKSUM
The two's complement of the one byte sum of the MESSAGE and the BYTE
COUNT.
The purpose of the checksum is to verify that all the bytes in the message that contain variable data
have been received properly. The STX is the only byte that has a fixed value, so it is the only byte not
included in the checksum calculation. The checksum is calculated by adding all the variable bytes
together. The least significant byte of this sum is then subtracted from 100 hex to compute the
checksum. To verify that the checksum is computed correctly, add all the bytes including the checksum
but excluding the STX together. The least significant byte of the sum should be zero if the checksum is
computed correctly.
The MESSAGE consists of a command and optional bytes of data and is structured as follows:
COMMAND
COMMAND
Single byte command directed to device.
DATA 1...DATA n Variable length, any arguments required by COMMAND.
If the command message was not accepted by the Device due to a checksum error, parity error or an
invalid command the Device will respond with an NAK (05 hex) character and re-enter the SELECT
state.
If the command message is accepted by the Device and there is no data response required, it will
respond with an ACK (04 hex) character and re-enter the SELECT state.
If the command message requires a data response, the Device will transmit a response message
structured as follows:
STX
Start of message character (02 hex).
BYTE COUNT
Count of response message not including STX, BYTE COUNT or CHECKSUM.
COMMAND ECHO
Command message echoed.
MESSAGE
Variable length response message consisting of the data requested by the
command message.
CHECKSUM
The two's complement of the one byte sum of the COMMAND ECHO,
MESSAGE and the BYTE COUNT.
For example, to request the current time code data in BCD format from the reader, the command
message would be transmitted as follows:
02
STX
If the current LTC reader time code was 12:45:30:00 Drop Frame the response message would be
received as follows:
02
07
66
STX
BYTE
CMD
COUNT
(SENSE
RDR)
Page 4-4
DATA 1
02
BYTE COUNT
SENSE RDR
01
00
CMD
DATA 1
DATA
(FRMS)
(BLOCKS)
Revision 1.5.1
.....
66
BLOCKS
30
45
DATA 2
DATA 3
(SECS)
(MINS)
DATA n
01
97
CHECKSUM
12
01
DATA 4
DATA 5
(HRS)
(FLAGS)
SERIAL PROTOCOL
0A
CHKSUM
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