Omron SYSMAC CJ - REFERENCE MANUAL 01-2008 Reference Manual page 1073

Network Instructions
Execution
b
condition
(Executing)
d (Execution completed)
a (Executing)
b (Executing)
c (Executing)
1034
Example of Previous Programming Requirements
Exclusive control was required by the user when the same communications port was used more than once.
Confirmation of the availability of a communications port
was required using the corresponding Communications Port Enabled Flag, here for port 0.
A20200
KEEP
a
(Executing)
@Communica-
tions instruction
Communica-
tions port: 0
Exclusive control was required by the user when
the same communications port was used more than once.
@Communica-
tions instruction
It was necessary to keep track of the communications
port being used by each instruction.
Communica-
tions port: 0
@Communica-
tions instruction
Communica-
tions port: 1
Now, for CS1-H, CJ1-H, CJ1M, and CS1D CPU Units of lot number 020601 or
later (manufactured 1 June 2002 or later), the port number can be specified
as "F" instead of from 0 to 7 to automatically allocate the communications
port, i.e., the next open communications port is used automatically.
@Communica-
tions instruction
Communica-
tions port: F
This saves the programmer from having to keep track of communications
ports while programming. The differences between assigning specific port
numbers and automatically allocating port numbers are given in the following
table.
Item
Specification of the com-
munications port number
in the control data
Exclusive control
Flag applications
Network communica-
tions completion codes
When "F" is specified, the next available
communications port is used automatically.
Specific number
assignments
0 to 7 F
Required. Not required unless more than 8
communications ports are
required at the same time.
LD or LD NOT used TST(350) or TSTN(351) used with
with flag corre- A218 (Used Communications Port
sponding to the Number).
specified communi-
cations port.
Completion code for Completion codes are accessed
communications by using the I/O memory address
port specified by stored in A216 and A217 (Network
user is accessed. Communications Completion
Code Storage Address) and index
register indirect addressing.
Section 3-25
Automatic allocation