I/O configuration variants
6.6 Versions of I/O connection to the PROFINET IO interface
CPU 410 Process Automation/CPU 410 SMART
78
System Manual, 05/2017, A5E31622160-AC
Configuration
The following figure shows an example for the connection of the sensors or actuators each
with two redundantly used input/output modules.
Figure 6-11 S7-400 H-system with sensors and actuators on module pairs (redundant signal processing)
Response to failure
The following applies when a I/O module or a channel of the two I/O modules fails (valid for
input/output and mixed modules):
●
The inputs continue to be available in the system.
●
The outputs are controlled in the system.
Connecting sensors/actuators
You can connect a sensor/actuator to two redundant input/output modules.
The failure of an input module does not result in the loss of sensor data. When an output
module fails, the connected actuator continues to be controlled.
In some cases, the hardware design requires the sensor also to be implemented
redundantly, for example for RTD thermal resistors. Sensors can be powered using suitable
input modules.
The redundant signal processing of the sensors and actuators at the module level increases
the availability of the system. Firmware update and module replacement are possible during
operation.
In redundant operation, the switching characteristics of the output modules that can control
the actuator in parallel are improved. The modules can operate with twice the switching
current and power distribution between two output modules.
The figure below shows a configuration with one sensor and one actuator for a pair of
redundant I/O modules.