Mitsubishi Electric SW0DNC-MNETH-B User Manual page 162

12 APPLICATION FUNCTIONS
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< Operation when 128 received data are already stored in the reception buffer of
the driver >
When 128 received data are already stored in the reception buffer of the
driver, the subsequent data are received by the board once, but the driver
automatically discards those received data at the time of storage to the
reception buffer of the driver.
When the sending side sent data with "arrival acknowledgment" execution
type, the process of send data is completed normally at the sending side,
but data are discarded.
Sending station
Data sent from
other station by
the SEND
instruction
< Precautions for using RECV function >
1
When receiving data to the multiple channels of the board,
create a user program to read data from all channels that
receive data.
If a channel from which data are not read exists in the
channel from which data are received, the received data of
the channel from which data are not read are accumulated in
the reception buffer of the driver and all areas of 128 data
are occupied.
In this case, the received data of other channels cannot be
read because the driver automatically discards subsequent
data received by the board.
2
When attempting data read by executing the mdReceive
function immediately after the send data completion at the
sending station, an error, "71 (0047H): No reception data
error", occurs because the driver has not completed the
RECV function and thus the receive data have not yet stored
to the reception buffer of the driver.
Retry the operation after waiting for a while.
Driver
Reception buffer of driver
Received data of Channel 3
Received data of Channel 7
Board
Received data of Channel 1
Channel 1
Received data of Channel 5
Channel 2
Channel 3
Received data of Channel 4
Channel 4
Channel 5
Channel 6
Channel 7
Received data of Channel 2
Channel 8
Received data of Channel 6
Received data can be stored
up to 128 disregarding the
channel numbers.
Discards received data
MELSEC
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