Siemens Industry Online Support
Siemens AG
Entry type: FAQ, Entry ID: 18794463, Entry date: 09/17/2007

Why doesn't the compiler setting "Cyclic Action with RLO = 0" deliver the required result?

  • Entry
  • Associated product(s)

If the compiler setting "Cyclic Actions with RLO 0" is activated, the cyclic actions in a particular state are performed once again with an RLO (result of logical operation) = 0 upon exiting the state. Consequently, all the signals which were set during that state are reset.
This compiler setting is ineffective if (=) conditions have been programmed in front of the assignments in the cycle actions.

You can enable or disable the die "Cyclic Actions with RLO 0" setting in the S7 graph group via "Options > Graph group(1) settings ... > Tab: Compile".

When this state is exited, the RLO formed by the conditions previously is retained; it is not reset to zero.

All the binary signals, which are meant to deliver a value of "0" when the current state ends, have to be programmed with the "R command" when exiting the state, for example "X: R M20.0". Fig. 01 shows an example of how the binary signals are reset in exit actions.

Fig. 01

There is further information available in the current readme file (section 2.21).

The problem described above no longer occurs from S7-HiGraph version 5.3 onwards.

Security information
In order to protect plants, systems, machines and networks against cyber threats, it is necessary to implement – and continuously maintain – a holistic, state-of-the-art industrial security concept. Siemens’ products and solutions constitute one element of such a concept. For more information about industrial security, please visit