Send Procedure; Procedure Exists - Mitsubishi Electric MELSEC iQ-RJ71EN71 User Manual

Send procedure

The following figure shows the processing when sending data from the RJ71EN71 or the RnENCPU (network part) to the
external device.

Procedure exists

The following figure shows the send processing for the fixed buffer No.1 area corresponding to the connection No.1.
Initial processing Open processing
'Initial status' (Un\G1900024.0)
'Open completion signal
(connection No.1)'
(Un\G1900000.0)
BUFSND instruction
BUFSND instruction completion
device
BUFSND instruction completion
device +1
 Normal completion of the initial processing is checked. ('Initial status' (Un\G1900024.0): On)
 A connection is established between the external device and the RJ71EN71 or the RnENCPU (network part), and normal completion of the connection No.1
open processings is checked. ( Page 378 TCP/IP Communications, UDP/IP Communications)
 The BUFSND instruction is executed. (Sends data)
 The data length amount of send data in the fixed buffer No.1 area is sent to the external device.
 When the external device receives the data form the RJ71EN71 or the RnENCPU (network part), returns a response to the RJ71EN71 or the RnENCPU
(network part).
 When a response is received from the external device, the RJ71EN71 or the RnENCPU (network part) finishes data send. If the response is not returned
within the response monitor timer value, a data send error occurs.
the send processing.
*1 Adjust the monitor timer value with the parameters. ( Page 260 Timer Settings for Data Communication)
• The details of the open setting are enabled at the rising edge of the RJ71EN71 and the RnENCPU (network
part) open completion signal.
• Send the next data (command) after the data exchange has been completed for the previous data
(command) send.
• When sending or receiving data to multiple external devices, the data can be sent sequentially. However, to
avoid communication trouble, it is recommended to switch the external device and send/receive the data.
When using a connection opened with UDP/IP, the setting value in the communication address setting area
can be changed before sending or receiving to switch the external device.
Sending data
Ò
Ó
Sending data
*1
If the data send completes abnormally, execute the BUFSND instruction again and start
Receiving a response
Ô
ACK
(TCP only)
ACK
Response (TCP only)
Õ Ö
1.5 Communications Using the Fixed Buffer
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