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RDMDW charges pseudo - random number with 32 bits in length in the format DWORD. This is the PLC's internal timer that is read and is transferred into a pseudo random number. Since RDMDW as a function and was not written as a function module, it can not save data between 2 calls and should therefore be used with caution. If RDMDW called only 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). If it be called only once per cycle, it is sufficient to call RDMDW(0). As a starting number for each call, the last number accounted by RDMDW be used. That result from RDMDW is a random 32-bit wide bit pattern. |
