Siemens SIMATIC S5-100U System Manual page 458

Function Modules
Addressing
The module is addressed like a four-channel analog module.
Operating Modes
Since transducers and sensors are directly wired to the module, the module can work independently
from a programmable controller in stand-alone operation, provided that the setpoints and the 24-V
power supply voltage are fed directly to the IP 262. This means that the module executes the
control and the output of the manipulated variable and can work alone or be controlled via the
SINEC L1 by a master unit.
Besides this, the IP 262 has its own back-up, which means that the module can continue to work
alone in the event the master CPU (e.g., S5-135U with R64) fails. It uses the last setpoint received
from the CPU or the predefined back-up setpoint.
Two operating modes are possible:
• DDC Operation (Direct Digital Control)
The control is executed entirely from the CPU. The IP only outputs the manipulated variable. If
the CPU fails, the module can continue to control independently with a predefined back-up
setpoint.
• SPC Operation (SetPoint Control)
The module receives only the setpoint from the CPU; the control task is carried out
independently of the CPU. If the CPU fails, the IP continues to control using the last setpoint
received from the CPU. It is also possible to use a predefined back-up setpoint here.
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S5-100U
EWA 4NEB 812 6120-02b