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COMMUNICATION USING MC PROTOCOL8
8 - 1
8
MELSEC-F
8 COMMUNICATION USING MC PROTOCOL
This chapter gives an overview of the MC protocol.
NOTE
The frame type of MC protocol (data communication messages) used by the
external device to access the PLC via this product is equivalent to A compatible 1E
frame.
8.1 Data Communication Function
The MC protocol is the abbreviated name of the MELSEC protocol that is a
communication system for the PLCs. Using this protocol, the external devices can
read or write device data from/to the PLC via the Ethernet module.
Any external devices on which application programs can be installed and which can
send and receive data in accordance with the MELSEC PLC protocol can access the
PLC using MC Protocol.
8.1.1 Accessing the PLC using MC protocol
This section explains the main functions for accessing the PLC using MC protocol.
On the PLC side, the Ethernet module sends and receives data based on the
instructions (protocol) from the external devices, so the PLC side does not require
sequence programs for data communication.
(1) Data read/write
This function reads/writes data from/to the PLC device memory to which the
Ethernet module is connected.
By reading and writing data, the PLC operation monitoring, data analysis and
production management can be performed on the external device side.
L
H
H
Head device
Text (Command)
ACPU
monitoring
timer
PC
No.
Subheader
Header
Ethernet
(14 bytes)
IP
(20 bytes)
TCP
/
UDP
L
(Command message for the A compatible 1E frame)
Number of
device points
00
H
0A
H
00
H
00
H
00
H
00
H
20
H
40
H
0C
H
00
H
FF
H
64
H
(Example)