882
Network Instructions Section 3-24
The following table shows relevant bits and flags in the Auxiliary Area.
Precautions If the Communications Port Enabled Flag is OFF for the port number specified
in C+4, the instruction will be treated as NOP(000) and will not be executed.
The Error Flag will be turned ON in this case.
When data will be transmitted outside of the local network, the user must reg-
ister routing tables in the PLCs (CPU Units) in each network. (Routing tables
indicate the routes to other networks in which destination nodes are con-
nected.)
Refer to the FINS command response codes in the CS/CJ/CP Series Com-
munications Commands Reference Manual (W342) for details on the comple-
tion codes for network communications.
Communications port numbers 00 to 07 are shared by the network and serial
communications instructions (SEND(090), RECV(098), CMND(490),
PMCR(260), TXDU(256), or RXDU(255)), so only one of these instructions
may be executed for a communications port at one time. To ensure that
CMND(490) is not executed while a port is busy, program the port’s Communi-
cations Port Enabled Flag (A202.00 to A202.07) as a normally open condition.
Noise and other factors can cause the transmission or response to be cor-
rupted or lost, so we recommend setting the number of retries to a non-zero
value which will cause CMND(490) to be executed again if the response is not
received within the response monitoring time.
Examples The following program section shows an example of sending a FINS com-
mand to another CPU Unit.
When CIO 0.00 and A202.07 (the Communications Port Enabled Flag for port
07) are ON, CMND(490) transmits FINS command 0101 (MEMORY AREA
READ) to node number 3. The response is stored in D200 to D211.
The MEMORY AREA READ command reads 10 words from D10 to D19. The
response contains the 2-byte command code (0101), the 2-byte completion
code, and then the 10 words of data, for a total of 12 words or 24 bytes.
The data will be retransmitted up to 3 times if a response is not received
within ten seconds.
Name Address Operation
Communications
Port Enabled Flag
A202.00 to
A202.07
These flags are turned ON to indicate that net-
work instructions, including PMCR(260) may be
executed for the corresponding ports (00 to 07).
A flag is turned OFF when a network instruction
is being executed for the corresponding port and
turned ON again when the instruction is com-
pleted.
Communications
Port Error Flag
A219.00 to
A219.07
These flags are turned ON to indicate that an
error has occurred at the corresponding ports (00
to 07) during execution of a network instruction.
The flag status is retained until the next network
instruction is executed. The flag will be turned
OFF when the next instruction is executed even if
an error occurred previously.
Communications
Port Completion
Codes
A203 to
A210
These words contain the completion codes for the
corresponding ports (00 to 07) following execu-
tion of a network instruction.
The corresponding word will contain 0000 while
the network instruction is being executed and the
completion code will be written when the instruc-
tion is completed. These words are cleared when
program execution begins.
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