Sunday, July 10, 2011

Splitting I/O between Child and Parent PLCs





A child PLC has the splitting selection of its fixed resources of I/O with the its parent PLC—e.g. the child keeps control through some of its own fixed I/O while the parent controls the others. The points of I/O controlled by the child PLC have to be addressed in the map of child’s I/O, and the points of I/O controlled by the parent PLC have to be addressed in the map of parent’s I/O when the resources of fixed I/O are split. The means to splitting I/O is selecting the proper location types and locating them in the I/O map screens of the child and parent. For instance, if a child has 12 outputs of fixed FET, you can address the I/O one PLC’s I/O map with a MIC138 location type by putting 8 FET outputs under its control and the other map of I/O with a MIC139 location type by putting the leaving four FET outputs under the other control of PLC.

Both PLCs will interpret the same data input. Shared of data input will not cause clashes between the child and parent PLC, and, then, the similar fixed inputs can be planned in both the child and the parent PLC. Though, have both PLCs write the similar output data can bring in errors. If the similar outputs are planned in both PLCs, the system will record an error against the parent PLC, and it will be signed damaging in the table of PLC status.

Splitting I/O
The two of I/O map screens from MODSOFT Lite. They demonstrate how the 12 outputs of fixed relay a PLC of 110CPU51200 constructed as a child PLC can be split between it and its parent PLC. The map of the child I/O PLC can be accessed by the parent PLC. This screen of I/O map is built while the panel of programming is linked to the parent PLC. The type of location for the discrete I/O is MIC129, representing that the parent PLC can access eight outputs of the child’s fixed relay. Screen 2 is the child I/O map that stays under the control of the child. This map of I/O is made while the panel of programming is linked to the child PLC. The type of location for the discrete I/O is MIC130, representing that the child preserves control over four outputs of its fixed relay.



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