Example 2 of an Exchange from a Slave to a Slave System
(Original Document)
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At a Glance
The slave address Ad1 = 7 reads a 5-word table, using the function SEND_REQ, in the slave PLC with the address Ad0 = 9.
Transmission
The PLC sender generates a request with the code 16#0036 (read objects):
SEND_REQ(ADDR('0.0.1.7'), 16#0036, %MW200:6, %MW220:4, %MW210:6)
Parameters of the request:
Parameters
Description
ADDR(‘0.0.1.7’)
  • 0 : rack
  • 0 : module
  • 1 : channel 1
  • 7 : transmitting address Ad1
16 #0036
unsolicited data request
%MW200 = 16#FE 00
destination slave address (Ad0 = 9)
%MW201 = 16#FE 05
%MW202 = 16#00 09
%MW203 = 16#07 68
  • type of object = 07 (16 bit integer)
  • segment = 68 (internal words)
%MW204 = 50
in decimal, origin of the table of words to read
%MW223 = 12
transmission of 6 words (12 bytes)
NOTE: Once the function has finished execution, the length word in the report is:
%MW223 = 11 (reception of 11 bytes = 10 (5 words) + 1 (object type)).
Reception Table
Table of read words:
Byte 1
Byte 0
%MW210 =
Least significant byte of first word
07 : type of objects read
%MW211 =
Least significant byte of second word
Most significant byte of first word
%MW212 =
Least significant byte of third word
Most significant byte of second word
%MW213 =
Least significant byte of fourth word
Most significant byte of third word
%MW214 =
Least significant byte of fifth word
Most significant byte of fourth word
%MW215 =
not significant
Most significant byte of fifth word
The least significant byte of the first word read contains the type of objects read, the reception table is thus shifted by 1 byte.
An additional word must therefore be provided in the reception table. The data processing requires an algorithm for processing this shift. For Premium PLCs, this algorithm is provided by the function ROR1_ARB.