Specifications

2 - 16

(3) Close processing

(a) The close processing is a processing which disables data communication

with external devices.

1) In TCP/IP communication

• The Ethernet module system communicates with the external device

using the connection used in data communication and disconnects the

connection (disconnection of logic circuit).

• Completing the close processing normally enables change of the

external device that uses the connection.

2) In UDP/IP communication

• The Ethernet module system performs the internal processing.

• Completing the close processing normally enables change of the

external device that uses the connection.

(b) The close processing is performed mainly in the following cases.

• Terminate a connection with an external device

• Change an external device to communicate

• Change communication conditions

that has been opened using the sequence program.

(d) Determine the timing for the close processing with the external device.

POINT

Even if the close processing is not requested, the open completion signal

(corresponding bit in address: 5000

H) automatically turns off and the

communication line is closed in the following cases:

(1) When an existence confirmation function time out occurs.

(2) When a close or ABORT (RST) instruction is received from an external device.

(3) When the Active open request is received again from the external device in the

open completion status of TCP/IP. (The connection will be closed after the RST

command is sent.)