ABB 500 Series Builder's Manual page 85

Configuring the 56/64 kbit data
communication modules
 &KHFN WKDW WKH RSWLFDO EXGJHW LV FRUUHFW
 &20)$,/ RFFXUV IRU WKH IROORZLQJ UHDVRQV
The COMFAIL signal will be triggered when there is a problem in the communication
link between the two terminals, depending on type of 56/64 modem. Also, normal ac-
tions such as a change of setting, switch off of remote terminal during maintenance etc.,
can cause COMFAIL.
&RPIDLO IXQFWLRQ
COMFAIL triggering according to table
COMFAIL
Drop-out delay; t = 200ms
)LJXUH  &RPIDLO WULJJHULQJ
The 200 ms alarm dropout delay is, for example, required as hysteresis for terminals
with reserve overcurrent, REL 551 or distance reserve function REL 561, if the differ-
ential function is blocked by communication delays and interruptions etc.
The communication failure signal, COMFAIL, depends on the following internal sig-
nals (variables) in each terminal for REx 5xx.
tional explanations below.
,QVWDOODWLRQ RI WKH RSWLFDO FDEOHV LQ
t
en03000125.vsd
Table 42
&KDSWHU 
WHUPLQDOV DQG FXELFOHV
shows a summary with addi-
79