Chapter 4. Ladder Diagram (LD) Programming158 PACSystems* RX7i, RX3i and RSTi-EP CPU Programmer's Reference Manual GFK-2950C4.8.9 Data Initialize Communications RequestThe Data Initialize Communications Request (DATA_INIT_COMM) function initializes aCOMMREQ function with a block of constant data. The IN parameter of the COMMREQmust correspond with output Q of this DATA_INIT_COMM function.When DATA_INIT_COMM is first programmed, the constants are initialized to zeroes. To specify theconstant data to copy, double-click the DATA_INIT_COMM instruction in the LD editor.When DATA_INIT_COMM receives power flow, it copies the constant data to output Q.DATA_INIT_COMM’s constant data length operand specifies how many words of constant data tocopy to consecutive reference addresses starting at output Q. The length should be equal to the sizeof the COMMREQ function’s entire command block. DATA_INIT_COMM passes power to the rightwhenever it receives power.Note: The output parameter is not included in coil checking.OperandsParameter Description Allowed Operands OptionalLength The number of WORDs (default 7) of constant datacopied to consecutive reference addresses starting atoutput Q. Must equal the size of the COMMREQfunction’s entire command block, including the header(words 0-5).Constant NoQ The beginning address of the area where the data iscopied.R, W, P, L, AI, AQ, andsymbolic non-discretevariablesNoExampleOn the first scan (as restricted by the #FST_SCN systemvariable), a command block consisting of 100 words ofdata, including the 6 header words, is copied to %P00001through %P00100. %Q00002 receives power.
