Interconnection Of Redundant Inputs And Outputs - Siemens Add 7 AddFEM Manual

Mode of Operation
Signals from the Host to the AddFEM
Signal name
LZ
MRV
ZRV
3.3.6

Interconnection of Redundant Inputs and Outputs

In order to implement redundant control of actuating elements all the analog and
digital outputs of one AddFEM can be connected in parallel with the outputs of the
same type of another AddFEM. The same procedure can be applied to analog vol-
tage inputs and digital inputs.
Redundant analog current inputs, on the other hand, have to be connected in se-
ries. Note that external Zener diodes (for types see Fig. 3-12) have to be connec-
ted parallel to the inputs, so that the current can continue to flow (via these exter-
nal Zener diodes) when an AddFEM is replaced.
Note:
Redundant AddFEMs have to assigned absolutely symmetrically with I/O signals.
Analog Outputs
Analog outputs of redundant AddFEMs are activated or passivated in accordance
with the module status (master or reserve).
There is no load distribution for redundant analog outputs – so that a subdivision
50%/50% to both redundant AddFEMs is not possible.
3-20
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Meaning
Sign of life 0x5/0xA = Active channel
0x3/0xC = Passive channel
Master/Reserve 0 = Master; 1 = Reserve
specification
Forced reserve 0 = Irrelevant; 1 = Forced reserve
specification
AddFEM
Value
AddFEM
C79000–G8076–C900–03