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Figure 898: A typical help contact is edited.
A typical help symbol undergoing editing is shown in the figure above.
Important facts to consider when planning to create a conventional help symbol for a contact, are the function code to use, the number of connection points, and the sequence of those connection points. If those do not match, mirror booking will not work properly.
Mirror booking for single contacts is limited to a maximum of three connection points per contact. That is of course all that is needed for make, break, and change-over contacts. Please note that these limitations do not apply for PLC help symbols. Besides that, there is also another exception from this rule, namely that you can create help symbols that represents multiple contacts (functions) in one single symbol. Please refer to the Help symbols for multiple contacts topic.
If you are unsure of the number of connection points for a certain function code, you can check that in the Function codes tab of the Settings module. There, you can also create your own function codes, if a need for that would ever appear.
You can create symbols for contacts from scratch, without any limitations. However, since contacts typically look very similar, you are in most cases better off if you create your symbol from an existing one instead.
There are a large number of function codes reserved for contacts of different kinds, and it is of course important to select the correct one for mirror booking to work properly. Please refer to the Technical details topic for a complete documentation of all standard function codes that are available for contacts. Please also note that you can add additional contact types if a need for that would arise.