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MELSEC-Q
7 APPLICATION FUNCTIONS
7.4.3 Group function
The group function is used to group the target stations of a transient transmission and
send data to all of the stations in a group with a single instruction. One network may
have a maximum of 32 groups.
By setting a group specification to the target station number in the control data of a
dedicated link instruction, stations with the matching group number retrieve the
transient data.
However, whether or not the transient transmission is normally completed cannot be
verified because the data is transmitted to multiple stations.
(1) Visual representation of the function
The following figure shows an example of grouping. When a transient
transmission is executed by specifying group number 1, all of the three stations,
1N
S3, 1NS5 and 1NS6, retrieve the transient data.
1M
P
1
1N
S
2 1N
S
3
Group No. 1
1N
S
6 1N
S
5 1N
S
4
Group No. 1 Group No. 1
(2) Setting method
Set the group number of the target network module using the following network
parameters from GX Developer.
Set the desired group number.
Setting
Item
Valid setting range Default
Parameter screen Group No. 1 to 32 0 (no group specification)
Control data target station No. 81
H
(1) to A0
H
(32)
(3) Transient transmission instructions that allows group specification
No. Instruction Description Reference
1 SEND Data sending Section 7.4.5 (1)
2 (S)WRITE Writes to word device of other station Section 7.4.5 (2)
3 REQ Requests transient transmission to other station Section 7.4.5 (3)
4 ZNWR Writes to word device of other station Section 7.4.5 (4)
5 RRUN Remote RUN Section 7.4.5 (5)
6 RSTOP Remote STOP Section 7.4.5 (5)
7 RTMWR Writes other station clock data Section 7.4.5 (6)
8 Clock setting GX Developer Section 7.4.7
9 Remote RUN/STOP GX Developer GX Developer Operating Manual
POINT
The execution of the transient transmission using the group function cannot be
verified.
When this mode of transient transmission is executed successively, a "No free area
in the receive buffer" (error code: F222) may occur. Design the system thoroughly
to allow for a sufficient interval between executions, and make sure to test (debug)
to confirm that successive executions can be performed without generating any
error.
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