Using Socket Services by Manipulating Dedicated Control Bits

Section 6-7

Note The Open Flag will not turn ON at all if a force-close request is made during open processing.

6-7-8 TCP/IP Communications Programming Example

 

The following programming example illustrates transferring 100 bytes of data

 

between an Ethernet Unit and a host computer using TCP/IP communica-

 

tions.

System Configuration

The programming example uses the following system configuration. For the

 

TCP connection, the Ethernet Unit uses a passive open and the host com-

 

puter uses an active open.

Host computer

Ethernet Unit

 

 

PLC

 

IP address:

196.36.32.55

IP address:

196.36.32.101

 

Port number:

4096

Port number:

4096

Data Flow

The data will flow between the CPU Unit, Ethernet Unit, and host computer as

 

shown in the following diagram.

 

 

 

Line

Ethernet

Host computer

(Ethernet)

Unit

 

Sent to line.

 

Processing in

 

 

host computer

 

 

CPU Unit

Request Switches and ex- ecution bits turned ON (see note).

Execution bits turned OFF

Note Here, “execution bits” refer to CIO 000000 to CIO 000003, which are used in the ladder diagram to control execution of communications.

Basic Operations

CIO 000000 is turned ON to request opening a TCP socket from the Ethernet Unit.

CIO 000001 is turned ON to request closing the TCP socket from the Ethernet Unit.

CIO 000002 is turned ON to request sending data from the Ethernet Unit. Data (100 bytes) is sent beginning at D00000.

CIO 000003 is turned ON to request receiving data from the Ethernet Unit. The data that is received (100 bytes) is stored beginning at D01000.

One of the bits between CIO 000100 and CIO 000103 will turn ON if an error occurs. Refer to 6-7-5 Socket Service Request Switches for informa- tion on errors.

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Omron CJ1W-ETN21 8 TCP/IP Communications Programming Example, System Configuration, Data Flow, Basic Operations