Omron V750 series, Network Connection Manual

Page: 76 / 78

9. Program
9.7.2. TCP Connection Status Error and Corrective Actions
This section describes the situation in which the TCP connection status error occurs and
explains the corrective actions.
● Affects of the TCP connection status error
After a TCP connection status error occurs, if this program is executed again without any
corrective action or without notifying the error, then the destination node specified with the
destination IP address (
DstAdr
) input variable and destination port (
DstTcpPort
) input
variable may not be waiting for a connection. (Hereinafter this error is referred to as a
connect processing error.) This may be affected by the TCP connection status error that
occurred when the previous communication processing ended. (For error details, refer to
9.7.1 Error Code List
.)
● Situation in which the TCP connection status error occurs
Both a TCP connection status error after the close processing and a connect processing
error that occurs when the next communications processing is performed can be caused
by the fact that the close processing is not completed at the destination device. In this
situation, although all processing (until the close processing) of the program ended in the
Controller, the close processing completion notification is not received from the destination
device (It is not confirmed that the close processing is completed at the destination device).
● Corrective actions
The close processing may not be completed at the destination device. Check if the
communications port of the destination device is closed. If not closed or not possible to
check, reset the communications port of the destination device. The communications port
of the destination device can be reset by executing restart operation from the software or
by cycling the power supply. For details, refer to the manual for each destination device.
Precautions for Correct Use
Make sure the destination device is disconnected from other device before resetting the
communications port of the destination device.
● State of the Controller at a TCP connection status error
When a TCP connection status error occurs, the processing of this program is completed.
However, the resend/time monitoring function of TCP/IP , which is described in 9.3.2. Time
Monitoring Function, may be operating. This resend processing will stop in the following
cases. Therefore, you do not have to stop it.
•When a connect processing request is made again by re-executing the program
•When a communications problem such as cable disconnection is cleared during resend
processing
•When the resend processing is completed with the TCP/IP time monitoring (timeout)
function
•When the Controller is restarted or the power supply is turned OFF
73