Behavior During Operation; Example Of A Configuration Control - Siemens SIMATIC S7-1500 System Manual

9.2.7

Behavior during operation

Effect of discrepancy between station master and station option:
● For the online display and for the display in the diagnostics buffer (module OK or module
faulty), the station master is always used and not the differing station option.
Example: A module outputs diagnostics data. This module is configured in slot 4 in the
station master, but is inserted in slot 3 in the station option (missing module; see example
in the next section). In the online view (station master), slot 4 is indicated as faulty. In the
real configuration, the module at slot 3 indicates an error via an LED display.
If modules are entered as not present in the control data record, the automation system
behaves as follows:
● Modules designated as not present in the control data record do not supply diagnostics
and their status is always OK. The value status is OK.
● Direct writing access to the outputs that are not present or writing access to the process
image of outputs that are not present: Remains without effect; no access error is
signaled.
● Direct reading access to the inputs that are not present or reading access to the process
image of inputs that are not present: Value "0" is supplied; no access error is signaled.
● Write data record to module that is not present: Remains without effect; no error is
signaled.
● Read data record from module that is not present: An error is signaled because a valid
data record cannot be returned.
9.2.8

Example of a configuration control

A station master consisting of a system power supply, CPU, and three I/O modules is
configured in STEP 7 in the following section.
The module at slot 3 is not present in the station option 1 and is "hidden" by the configuration
control.
In the station option 2 the module that was initially hidden is located in the last slot. The
added slot is made known to the CPU by a modified control data record.
Automation system
System Manual, 12/2014, A5E03461182-AC
Flexible automation concepts
9.2 Configuration control
139