Mitsubishi MELSEC-A Series Reference Manual page 248

9. PROGRAMMING
(4)
(5)
(b) Set link refresh disable area as shown below when using a module which can
make rink refresh execution disable setting such as the AnNCPUP21/R21 by
using ON/OFF of M9053 and the DI/EI instructions.
(c) The module that performs link refresh only after the execution of the END
instruction in the sequence program (A3HCPU, A3MCPU, AnACPU, AnUCPU,
A2USCPU(S1), QnACPU, QnAS(H)CPU(S1)), even if data of two words or more
are sent to link registers, the old and new data are not mixed.
Precautions when using the MELSECNET
composite mode
The timing to be link refreshed may differ between the device range assigned with
the first half of the link parameters and that assigned with the last half of the link
parameters.
Handshake processing is required to receive the data written at the same timing.
Read/write of the special function module installed to the remote I/O station
(a) Execute the RFRP or RTOP instruction after initial communications of remote I/O
stations.
The completion of initial communications can be checked with special link
registers (D9224 to D9227). (Refer to the ladder examples in Section 9.8.)
If the RFRP or RTOP instruction is executed before the completion of initial
communications, an "OPERATION ERROR" occurs.
mode or the MELSECNET
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