Siemens siprotec 7SA6 User Manual page 581

RS485
Termination
Analog Outputs
Time
Synchronization
Interface
Optical Fibres
7SA6 Manual
C53000-G1176-C133-1
The RS485 interface is capable of half-duplex service with the signals A/A' and B/B'
with a common relative potential C/C' (DGND). Verify that only the last device on the
bus has the terminating resistors connected, and that the other devices on the bus do
not. The jumpers for the terminating resistors are on the interface module RS485
(Figure 8-18) or on the Profibus module (Figure 8-19).
If the bus is extended, make sure again that only the last device on the bus has the
terminating resistors switched in, and that all other devices on the bus do not.
Both analog values are directed as current via a 9-pole D-subminiature female
connector. The outputs are isolated.
Table 8-24 Pin-assignments for the
output
Pin-No. Designation
1 Channel 1 positive
2 –
3 –
4 –
5 Channel 2 positive
6 Channel 1 negative
7 –
8 –
9 Channel 2 negative
5 VDC, 12 VDC or 24 VDC time synchronization signals can be processed optionally
if the connections are realized as indicated in Table 8-25.
Table 8-25 Pin-assignments for the D-subminiature port of the
interface
Pin-No. Designation
1 P24_TSIG
2 P5_TSIG
3 M_TSIG
4 –*)
5 Screen
6 –
7 P12_TSIG
8 P_TSYNC*)
9 Screen
*) assigned, but not available
Signals transmitted over optical fibres are unaffected by interference. The fibres
guarantee electrical isolation between the connections. Transmit and receive
connections are identified with the symbols
Installation and Commissioning
D-subminiature female connector
Signal meaning
Input 24 V
Input 5 V
Return Line
–*)
Shield potential
–
Input 12 V
Input 24 V*)
Shield potential
for transmit and
of the analog
time synchronization
for receive.
8-37