On-Demand Control Protocol - Mitsubishi Electric MELSEC FX Series User Manual

FX communication
8.10.2

On-demand Control Protocol

1 ) Control protocol programmable controller
On-demand data transmission
Set the word/byte data format
Set the on-demand data
Reset the on-demand error flag
Transmission error check
Error
Transmission Complete
2 ) Control protocol at computer
On-demand Receive
Check that the received data is
on-demand data.
Data processing
Completion of Receive
Start on-demand
No error
......
Set on/off special M8129.
ON: byte units(8bits), OFF: word units(16bits)
......
Write the data to be transmitted into data
registers.
......
Turn off on-demand error flag special M8128.
(If special M8128 is ON, on-demand can not
be started.)
......
On-demand is started by writing the head
device number where the data is stored into
special M8127, and writing the data length
into special D8128.
When the request is received, special M8127
is tur ned on, and when transmission is
completed, M8127 is turned off.
......
If the on-demand error flag special M8128 is
ON, the data was not transmitted due to a
transmission error.
......
On-demand data has a PLC number of "FE"
automatically attached. This can be used to
identify on-demand data.
Commands 8
8-16