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Communicating between OMRON PLCs Section 8-6
CMND(490) The CMND(490) instruction sends n bytes of command data, starting from the
beginning word S at the local node, to the node at node address N. the data in
m number of words, starting from the beginning word S at the remote node
(node address M) is received at the words starting from the beginning word D
at the local node.
Note The message services function does not guarantee that a message will reach
the destination node. A message may be lost during transmission due to fac-
tors such as noise. In order to prevent this from occurring when using mes-
sage services, it is common to set up retry processing at the node from which
instructions are issued. With the SEND(090), RECV(098), and CMND(490)
instructions, retry processing is executed automatically by specifying the num-
ber of retries, so specify a number other than 0.
S
15
0
(S−1)
+−
n
2
D
(D−1)
+−
m
2
Local node Destination node number N
Command
Response
Interpretation
Execution
Com-
mand
data: n
bytes
Re-
sponse
data: m
bytes
(@)CMND(490)
S
D
C
C+1
C
15 0
15 0
C+3
15 8 7 0
C+2 0 0
15 11 8 7 0
C+4 0 0
C+5
15 10 8 7 3 0
15 10 8 7 3 0
S: Beginning command storage word
D: Beginning response storage word
C: First word of control data (below)
Number of bytes of command data (n)
0000 to 07C6 (Hex): 1 to 1,990 bytes
Number of bytes of response data (m)
00 (Hex): Local network
01 to 7F (Hex): 1 to 127
Destination Unit address
00 (Hex): CPU Unit
10 to 1F: (Hex): Unit #0 to #15
E1 (Hex): Inner Board
FE (Hex): Unit connected to network
Destination node number N
00 to FE (Hex): 0 to 254
The same data can be broadcast to all nodes on the network by
setting the destination node number to FF (Hex).
The range of node addresses is different for networks other than Ethernet.
Number of retries
0 to F (Hex): 0 to 15 retries
Communications port number: 0 to 7
Response
0: Required.
1: Not required.
Response monitor time
0000 (Hex): 2 s
0000 to 07C6 (Hex): 1 to 1,990 bytes
Destination network number
0001 to FFFF (Hex): 0.1 to 6,553.5 s
(in units of 0.1 s)