Omron CJ - INSTRUCTIONS REFERENCE MANUAL 07-2009 Reference Manual page 901

3. Instructions
Example When Not Using Automatic Port Allocation
Execution
b
condition (Executing)
d (Execution completed)
a (Executing)
b (Executing)
c (Executing)
For CJ2 CPU Units and CS1-H, CJ1-H, CJ1M, and CS1D (Single CPU System) 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 communications
port number in the control data
Exclusive control
Flag applications
Communications Port Completion
Codes
864
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.
A202.00
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
When "F" is specified, the next available
communications port is used automatically.
User specification of
communications ports
0 to 7
Required
LD or LD NOT used with flag
corresponding to the specified
communications port.
Completion code for communications
port specified by user is accessed.
Automatic allocation of communications ports
F
Not required unless more than 8 communications ports are
required at the same time.
TST(350) or TSTN(351) used with A218 (Used
Communications Port Number).
Completion codes are accessed by using the PLC memory
address stored in A216 and A217 (Communications Port
Completion Code Storage Address) and index register
indirect addressing.
CS/CJ/NSJ Series Instructions Reference Manual (W474)