Data Receiving Procedure; Data Receiving Using The Main Program (Bufrcv Instruction) - Mitsubishi Electric MELSEC-L SERIES Basic User Manual

12.4

Data Receiving Procedure

This section describes how an E71 receives data from the connected device. The following methods for receiving data
are offered:

• Data receiving using the main program (BUFRCV instruction)

• Data receiving using an interrupt program (BUFRCVS instruction)
12.4.1
Data receiving using the main program (BUFRCV instruction)
A receive process in the main program is performed using the BUFRCV instruction.
(1) Procedure exists
The following is the data receive process performed in the fixed buffer number 1 area for the connection number
1.
Initial normal completion
Open completion signal
(address: 5000
BUFRCV instruction
BUFRCV instruction
completion device
BUFRCV instruction
completion device + 1
Fixed buffer reception status signal
(Address: 5005
Confirm the normal completion of the initial process. (Initial normal completion signal (X19): ON)
1
Establish a connection between the E71 and the connected device and confirm the normal completion of the
2
open process of the connection number 1.
Receive data from the destination.
3
• Fixed buffer reception status signal (address: 5005
Execute the BUFRCV instruction to read the receive data length and receive data from the fixed buffer
4
number 1.
• Fixed buffer reception status signal (address: 5005
When the receive data length and the receive data are completely read out, a response is sent to the
5
destination.
End the receive process. If the data receive process is abnormally ended, execute the BUFRCV instruction
6
again to repeat the receive process.
Initial process Open process
1
signal X19
2
[b0])
H
[b0])
H
CHAPTER 12 COMMUNICATIONS USING A FIXED BUFFER
Receiving data Sending a response
4
ACK
(TCP only)
3
(b0)): ON
H
(b0)): OFF
H
6
1 scan
ACK
(TCP only)
5
125
12