4 FDM - Frequency Deviation Monitoring
4.1.4.7 FDM Fingrid String
The fingrid telegram consists of a sequence of 34 characters and contains the reference time, the time deviation
and the frequency deviation. It ends with the characters carriage return (hex code 0Dh) and line feed (hex code
0Ah).
079:08:13:55.000 T+6.780F+0.012
<CR><LF>
079:08:13:55.000
reference time from the preconnected clock,
(yeardays:hours:minutes:seconds:milliseconds)
T+6.780
the time deviation between REF time and PL time,
with sign character (+/-), resolution: 1 ms
F+0.012
The frequency deviation between calculated and nominal frequency,
with sign character (+/-), resolution: 1 mHz
Configure the fingrid telegram for the corresponding serial interface and use the mode "On request only (?)".
Send
T
or
?
to get the respond string exactly with the change of the next second within 1 s.
Example for the request of the Fingrid time telegram:
Date:
20 March 2017
Time:
08:13:55 (UTC)
Time Deviation:
+6.780 s
Frequency Deviation:
+0.012 Hz
to FDM
←
T
or
?
(at 08:13:54.xxx)
from FDM
→
079:08:13:55.000 T+6.780F+0.012
<CR><LF>
To correct the time deviation TD, please use the specified format. If the time deviation TD is accepted,
the FDM confirms the command and applies the value within the next 2 seconds.
Example of setting TD to 6.780 seconds:
to FDM
←
F27 B3 PS +6.780
<CR><LF>
from FDM
→
F27
<CR><LF>
IMS-FDM Setup Guide
Date: 4th November 2020
21
