6F2S1916 (0.
5
)
GIF200
- 5 -
C37.94 frame from ‘0’ to ‘1’ for a return path from the GIF200 to the GRL2000. Incidentally,
the GIF200 sets all ‘1’ bits for the frames (alarm indication signal (AIS)) from GIF200 to the
MUX.
(iii)
Erroneous data with three yellow alarms (without LOS)
When ‘Yellow alarm bit’ and no erroneous signal (LOS) is found in the three consecutive
receive frames from the IED, it is considered the path is “Yellow”. During the Yellow path
condition, the GIF200 replaces the data bits to all ‘1’s for the frames from GIF200 to the IED,
and TX in C37.94 and RX in G.703 LEDs will be off. The Yellow path condition can be cleared
when ‘Yellow alarm bit’ is not found in the last three consecutive receive frames, or when the
LOS signal is detected.
Operations for detecting errors in G.703 and C37.94
Following cases show GIF200 operation against detection of erroneous data in G.703 and
C37.94 frames.
(i)
No data received in C37.94
If the GIF200 unit does not receive any data from the IED, it can be detected by the
bit-inversion check function and the GIF200 will set ‘1’ to “Yellow alarm bit” in TX data to be
sent to the GRL200 IED in C37.94 and to the MUX in G.703 (of which frame format is in
accordance with G.703). LEDs for CF in C37.94 will be on.
ITU-T G.703 I/F
GRL200
IED
GIF200 unit
AIS(Alarm
indication signal)
MUX
IEEE C37.94 I/F
(1)
No sending data
Data with “Yellow
alarm bit”
MUX
Data based on
G.703
(2)
(2)
Figure 2.7-1 IED sending data having errors
(ii)
LOS failure detected in GIF200
If the GIF200 unit receives erroneous data from the GRL200, which can be detected by the
LOS command, the GIF200 will set ‘1’ to “Yellow alarm bit” in TX data to be sent to the
GRL200, and all the bits will be set to ‘1’ (AIS) in G.703 frames for MUX. LED for TX in G.703
LEDs will be off and LED for CF in C37.94 will be on.
