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RDM calculates a pseudo- random number. This is the PLC's internal Timer read and converted into a pseudo-random number. Because RDM's is written as a function and not as a function module, it can not save data between 2 calls and should therefore be used with caution. RDM is only called once per cycle, it produces reasonable good results. But when it is repeatedly called within a cycle, it delivers the same number, most likely because of the PLC timer is still on the same value. If the function is repeatedly used within a cycle, so it must be passed with each call a different number of starts (LAST). It shall be called only once per cycle, is sufficient to call RDM(0). As a starting number for each call, the last calculated number of RDM can be used. Supplied by RDM random numbers between 0 and 1, which does not contain 1 (0 <=random number < 1) |
