Mitsubishi Electric MELSEC iQ-R Series User Manual page 241

Online and online (asynchronous mode)
The following explains the differences between 'online' and 'online (asynchronous mode)'.
■Online
A CPU module and a high speed data logger module synchronize each other and complete their start processing, then start at
the same time. (A CPU module stands by until a high speed data logger module completes its start processing.)
■Online (asynchronous mode)
A CPU module and a high speed data logger module start individually when their start processing is completed without waiting
for the completion of the processing of the other module.
Precautions
The following shows the considerations for using 'online (asynchronous mode)'.
• Do not access the buffer memory of a high speed data logger module until the module starts after a CPU module starts.
Otherwise, an indefinite value may be acquired and a sequence program may not run as intended.
When accessing the buffer memory, make sure that 'Module READY' (X0) is turned ON.
• Do not use dedicated instructions of a high speed data logger module until the module starts after a CPU module starts.
Otherwise, the high speed data logger module may not operate as intended.
When using dedicated instructions, make sure that 'Module operating status' (X5) is turned ON.
3 PARAMETER SETTING
239
3.2 Basic Settings
3