Controller Link Units Operation Manual

168
Introduction Section 6-1
2. With the message service, there is no guarantee that a message to a des-
tination node will reach its destination. It is always possible that the mes-
sage may be lost in transit due to noise or some other condition. When
using the message service, it is advisable to prevent this situation from oc-
curring by performing resend processing at the node where instructions
are issued. With the SEND, RECV, and CMND instructions, resend pro-
cessing is performed automatically once the number of retries has been
set, so be sure to specify a number other than “0” for the number of retries.
RECV RECV receives “m” words beginning with S (the beginning word for data
transmission at the destination node, M) to the words beginning with D (the
beginning word for data reception at the source node).
Note 1. When communicating with a CVM1 or CV-series PLC manufactured prior
to April 1996 on the local network, the local network address cannot be set
to “00.” Set a number other than “00” as the local network address in the
routing tables, and then specify that number.
2. With the message service, there is no guarantee that a message to a des-
tination node will reach its destination. It is always possible that the mes-
sage may be lost in transit due to noise or some other condition. When
using the message service, it is advisable to prevent this situation from oc-
curring by performing resend processing at the node where instructions
are issued. With the SEND, RECV, and CMND instructions, resend pro-
cessing is performed automatically once the number of retries has been
set, so be sure to specify a number other than “0” for the number of retries.
Destination node MSource node
@RECV(98)
S
D
C
"m" num-
ber of
send
words
D
15 0 15 0
…
m
S
Destination node M
01 to 20 (Hex): 1 to 32 (or 01 to 3E (Hex): 1 to 62)
The range of node addresses will vary for networks
other than Controller Link Networks.
C+1 0 0
C+3 0 0
Number of retries
0 to F (Hex): 0 to 15 retries
Communication port No.
0 to 7
0: Response required
1: Response not required
C+4
C
"m" number of send words
0000 to 03DE (Hex): 1 to 990 words
15 11 8 7 0
Destination network address
00 (Hex): Local network
01 to 7F (Hex): 1 to 127
C+2
15 11 8 7 0
Destination unit address
00 (Hex): PLC's CPU Unit
01 to 0F (Hex): Computer (user program)
10 to 1F (Hex): Unit nos. 0 to 15
E1 (Hex): Inner Board
FE (Hex): Unit connected to network
15 10 8 7 3 0
Response monitor time
0000 (Hex): 2 s
0001 to FFFF (Hex): 0.1 to 6,553.5 s
(Unit: 0.1 s)
If the baud rate is slow, then setting a small
value may generate an error. The standard is
approximately 4 seconds at 1 Mbps or 8
seconds at 500 Kbps.
15 0
S: Source node beginning send word
D: Destination node beginning receive word
C: Source node first control data word
…
(02 to 0F (Hex) are used
when using Controller Link
Support Boards for PCI Bus
only.)