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Chapter 7 Communication function
7-22
SD registration number shall be set the same as the number set to ARRAY segment in frame. If input variable in
Function Block remains blank, compile error may occurs. Thus, unused SD area as of DUMMY variable shall set
memory allocation to Auto and LENGTH to ‘0’. If no data is to be transmitted, in other words, ARRAY segment
registration is not applied in frame registration, set all areas of SD1 ~ SD4 to DUMMY variables with LENGTH all
set to ‘0’.
[Figure7.11] shows an example of variable setting of SD area. The system of [Figure 7.5] has set %MB0 area of
GLOFA-PLC to transmit 18 byte, thus memory allocation is allocated to %MB0 as user-defined and ARRAY
number is set to 18 from 0 to 17 the same as the number to be transmitted.
[Figure 7.11] Setting example of transmission data variable
Through the variable setting of transmission data as above, 18 byte data is transmitted from %MB0 via Write
request frame.