20
16-11
28
H-System – Isolated Barriers and Termination Boards for HIMA
Operation
Line Fault Transparency (LFT)
If the device has a signal output with line fault transparency, the fault message
can be transmitted on the signal lead. This saves additional wiring and delivers
channel-selective fault messages. For digital signals, a resistive passive
transistor output is used. Signals 0 and 1 are output using two resistance values
at the output. In the event of an fault, the output will become highly resistive. For
this line fault transparency function, corresponding input cards are required in the
controller.
Figure 4.2
Example of line fault transparency with digital input
Fault Signal on Termination Board
The majority of the termination boards have an internal fault signal.
Information about a missing supply voltage of the isolated barriers is available for
the system as a volt-free contact.
Wiring errors from field side will be reported via the same relay contact, if this
function supported by the the isolated barriers.
FAULT
SL2
5a
5b
SL1
8a
7a
