Siemens SIMATIC PCS 7

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I/O configuration variants

6.7 Connection of two-channel I/O to the PROFIBUS DP interface

CPU 410 Process Automation/CPU 410 SMART

96 System Manual, 05/2017, A5E31622160-AC

A configured substitute value of 0 mA will produce at least these output values. In a

redundant configuration of analog outputs, the substitute value of the current outputs is

automatically set permanently to "zero current and zero voltage". You can also specify a

configurable compensation current of 0-400 µA for an output range of 4-20 mA.

This means you have the option of matching the minimum/compensation current to the

connected I/O.

To minimize the error of the total current at the summing point in case of one-sided

passivation, the assigned compensation current is subtracted in this case from the current of

the depassivated (i.e., active) channel with a pre-set value of 4 mA (range +-20 µA).

Note

If both channels of a channel pair were passivated (e.g., by OB 85), the respective half of the

current value is still output to both storage locations in the process image of outputs. If one

channel is depassivated, then the full value is output on the available channel. If this is not

required, a substitute value must be writte

n to the lower channels of both modules prior to

executing FB 451 "RED_OUT".

Depassivation of modules

Passivated modules are depassivated by the following events:

● When the fault-tolerant system starts up

● When the fault-tolerant system switched to "redundant" mode

● After system modifications during operation

● If you call FC 451 "RED_DEPA" and at least one redundant channel or module is

passivated.

The depassivation is executed in FB 450 "RED IN" after one of these events has occurred.

Completion of the depassivation of all modules is logged in the diagnostics buffer.

Note

When a redundant module is assigned a process image partition and the corresponding OB

is not available on the CPU, the complete passivation process may take approximately 1

minute.

Siemens SIMATIC PCS 7 - Page 96