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3. Instructions
CS/CJ/NSJ Series Instructions Reference Manual (W474)
Network Instructions
3
Network Instructions
Network Communications Instructions for CJ1/CS1/CJ2
Communications Ports
There are 8 logical communications ports provided, so 8 communications instructions can be executed
simultaneously. Only one instruction can be executed at a time for each communications port. Exclusive
control must be used when more than 8 instructions are executed.
These 8 communications ports are shared by the network instructions (SEND(090), SEND2(491),
RECV(098), RECV2(492), CMND(490), CMND2(493), etc.), the serial communications instructions
(TXDU(256) and RXDU(255)), and the PROTOCOL MACRO instruction (PMCR(260) and
PMCR2(264)). Be sure not to specify the same port for two instructions at the same time.
Network Communications Instructions for the CJ1/CS1/CJ2 can be executed either by specifying a
communications port or by allowing the CPU Unit to automatically assign a port.
Each communications port can be used by only one instruction at a time. To specify a communications
port, the following steps were necessary.
• When programming, it was necessary to keep track of the ports that were being used to designate
only available ports in operands.
• In the ladder program, it was necessary to add processing to confirm the availability of
communications ports before using them.
Controller Link Unit,
Ethernet Unit, or Serial
Communications Unit
Port
CPU Unit
Instruction 1
Instruction 2
Instruction 3
Instruction 4
Instruction 5
Instruction 6
Instruction 7
Instruction 8
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