Omron CP - PROGRAMMING MANUAL 05-2007 Programming Manual page 891

Network Instructions
Timing the Execution of
Network Instructions
Execution Communications Port
Condition Enabled Flag
858
A Network Instruction just starts the communications processing when its
execution condition is established. The actual communications processing is
executed in the background in the "serial communications port servicing" por-
tion of peripheral servicing.
Directs the
start of
processing
only.
CMND
S
D
C
Stores results when
communications
processing is completed.
The communications processing is performed as follows:
1. If the corresponding Communications Port Enabled Flag (A202.00 to
A202.07) is ON when the execution condition is established, the system
performs the following processes:
• Turns OFF the port's Communications Port Enabled Flag and Commu-
nications Port Error Flag (A219.00 to A219.07).
• Sets the port's Communications Port Completion Code (A203 to A210)
to 0000.
• Reads the control words (beginning at C) and starts communications
processing (sending a FINS command or receiving a response.)
2. In the peripheral servicing's "serial communications port servicing" portion
of the cycle, the system composes a FINS command based on the oper-
ands (see note) and sends the FINS command to the Communications
Unit or other destination node.
Note When SEND(090) is being executed, the contents of S and D are
read and a FINS command for data transmission is composed.
When RECV(098) is being executed, the content of S is read and
a FINS command for data reception is composed.
When CMND(490) is being executed, the content of S is read and
the corresponding FINS command is composed.
3. If the send processing cannot be completed in a the time available in "serial
communications port servicing" period, the processing will be continued in
the next cycle's serial communications port servicing.
4. When a response is returned, the system performs the following process-
es:
• Refreshes the destination words specified in the Network instruction
with the response data.
• Turns ON the port's Communications Port Enabled Flag.
• Refreshes the port's Communications Port Error Flag (A219.00 to
A219.07) and Communications Port Completion Code (A203 to A210).
Background communications
processing
Cycle
time
Cycle
The communications processing
time
(transmission and reception) is
performed in time-slices over several
cycles during the peripheral
servicing's "serial communications
port servicing" portion of the cycle.
Section 3-24
Composes a FINS
command based on the
command data and sends it.
Receives the response and stores
the information as response data.
The communications results are
reflected in the allocated Auxiliary
Area Flags.