TTM 01-G Manual / October 2018
23
String-B Time Code O/P
Table 10 details the String B serial string format and fields.
About
This code substitutes a “Quality” indicator byte for the year field, but otherwise is identical
in form, function, and timing to String-A.
Timing
Transmitted once every second. The leading edge of the “start” bit of the first character
<SOH> is exactly on the second that the message describes.
Default Comms
9600 bps, 8-bit ASCII, no parity
Definition
<SOH>ddd:hh:mm:ssQ<CR><LF>
Placeholder
Content
<SOH>
Start Of Header: HEX 01
ddd
Day of Year: range “001” – “366”
:
HEX 3A
hh
hour: “00” – ”23”
:
HEX 3A
mm
minute: “00” – “59”
:
HEX 3A
ss
seconds: “00” – “59”
Q
“Quality” Character (detailed in Table 11)
<CR>
Carriage Return: HEX 0D
<LF>
Line Feed: HEX 0A
Table 10 - String B Time Code Format Fields
“Quality” Character (Q)
Content
HEX
ASCII
20
‘ ’ (space)
Clock is synchronized, timing accuracy is better than 60 ns
2E
‘.’ (full stop) Clock is accurate to 1 µs
2A
‘*’
Clock is accurate to 10 µs
23
‘#’
Clock is accurate to 100 µs
3F
‘?’
Clock accuracy may be worse than 100 µs
Table 11 - String B Quality Character 'Q' Indicators
Example:
Interpretation:
<SOH>112:12:34:36?<CR><LF>
day 112, time: 12:34:36, >100 µs sync error
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