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Chapter 4. Ladder Diagram (LD) Programming
4.8.9
Data Initialize Communications Request
The Data Initialize Communications Request (DATA_INIT_COMM) function initializes a
COMMREQ function with a block of constant data. The IN parameter of the COMMREQ
must 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 the
constant 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 to
copy to consecutive reference addresses starting at output Q. The length should be equal to the size
of the COMMREQ function's entire command block. DATA_INIT_COMM passes power to the right
whenever it receives power.
Note: The output parameter is not included in coil checking.
Operands
Parameter Description
Length
The number of WORDs (default 7) of constant data
copied to consecutive reference addresses starting at
output Q. Must equal the size of the COMMREQ
function's entire command block, including the header
(words 0-5).
Q
The beginning address of the area where the data is
copied.
Example
On the first scan (as restricted by the #FST_SCN system
variable), a command block consisting of 100 words of
data, including the 6 header words, is copied to %P00001
through %P00100. %Q00002 receives power.
158
PACSystems* RX7i, RX3i and RSTi-EP CPU Programmer's Reference Manual
Allowed Operands
Constant
R, W, P, L, AI, AQ, and
symbolic non-discrete
variables
Optional
No
No
GFK-2950C
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