Mitsubishi Electric MELSEC-L Series - Data Receiving Using an Interrupt Program (BUFRCVS Instruction)

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12.4.2 Data receiving using an interrupt program (BUFRCVS
instruction)
A receive process in an interrupt program is performed using the BUFRCVS instruction. An interrupt program is started
up when data is received from a connected device, and receive data for a CPU module can be read.
The following settings are required to use an interrupt program: ( Page 131, Section 12.5.1)
• Interrupt pointer setting
• Interrupt settings
(1) Procedure exists
The following is the receive process performed in the fixed buffer number 2 area for the connection number 2.
*1 If the data receive process is abnormally ended, the E71 does not return a response.
Confirm the normal completion of the initial process. (Initial normal completion signal (X19): ON)
Establish a connection between the E71 and the connected device and confirm the normal completion of the
open process of the connection number 2.
Receive data from the destination.
• Fixed buffer reception status signal (address: 5005
H
(b1)): ON
• Request the CPU module to start up the interrupt program.
The interrupt program starts up. Execute the BUFRCVS instruction to read the receive data length and
receive data from the fixed buffer number 2.
When the receive data length and the receive data are completely read out, a response is sent to the
destination.
*1
End the interrupt program to restart the main program.
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Initial
process
Open
process Receiving data
Initial normal completion
signal X19
Open completion signal
(address: 5000
H [b1])
Sending a response
In interrupt process
ACK
(TCP only)
ACK
(TCP only)
Cycle Cycle
Scan
END
process
Scan Scan
Program
END
process
BUFRCVS instruction
Receiving data
Response
Interrupt process
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