Chapter 8. Communication Function
8-69
Ex1) CD 6B B2 0E 1B
Function block input Input value
REQ Enter the input condition to operate
CH 16#0 or 0 Set channel 0
SLV_STNO 16#11 or 17 Slave station
FUNC 16#01 or 1 Enter ‘1’ when the Coil status is being read
SLV_ADDR 16#13 or 19
The start address to read from slave station
- Read the no. 19 to read starting from the Coil 00020 in accordance
with the previous no. 8) “Modbus addressing rules.” And the
highest data of the data address doesn’t need to be input.
Because it’s automatically processed by the input value of the
input FUNC of the function block.
NUM 16#25 or 37
The total data size to read
- Example is to be read 00020 ~ 00056, of which the total data size
is 37. Input 16#25 or 37.
z Results
Variable
Value to
save
Variable
Value to
save
Variable
Value to
save
Variable
Value to
save
RD_DB0[0] 1 RD_DB0[10] 0 RD_DB0[20]
1 RD_DB0[30] 0
RD_DB0[1] 0 RD_DB0[11] 1 RD_DB0[21]
1 RD_DB0[31] 0
RD_DB0[2] 1 RD_DB0[12] 0 RD_DB0[22]
0 RD_DB0[32] 1
RD_DB0[3] 1 RD_DB0[13] 1 RD_DB0[23]
1 RD_DB0[33] 1
RD_DB0[4] 0 RD_DB0[14] 1 RD_DB0[24]
0 RD_DB0[34] 0
RD_DB0[5] 0 RD_DB0[15] 0 RD_DB0[25]
1 RD_DB0[35] 1
RD_DB0[6] 1 RD_DB0[16] 0 RD_DB0[26]
1 RD_DB0[36] 1
RD_DB0[7] 1 RD_DB0[17] 1 RD_DB0[27]
1 RD_DB0[37] X
RD_DB0[8] 1 RD_DB0[18] 0 RD_DB0[28]
0 RD_DB0[38] X
RD_DB0[9] 1 RD_DB0[19] 0 RD_DB0[29]
0 RD_DB0[39] X
z The variable to which saves the previously read data must be array type. The size of array type must be the
same or bigger than the data size to read. If it’s smaller, the error code is marked in STATUS.
z The previously read data is saved from the array variable, RD_DB0[0].
z The remnant part of an array variable is redundancy, after the variable is filled with the previously read data.
To Next Page
Loading...
