Rockwell Automation 1768-EWEB EtherNet/IP Web Server Module User Manual - Manual (Page 134)

Publication ENET-UM527E-EN-P - October 2006
134 Socket Interface
Service Timeouts You must specify a Timeout parameter (in milliseconds) for any
service that might not complete immediately (OpenConnection,
AcceptConnection, Read, and Write). The timeout tells the Socket
Object the maximum amount of time it should wait when attempting
to complete the service. While waiting for the service to complete, the
MSG instruction is enabled.
If the requested service does not complete before the Timeout period
expires, the Socket Object returns a response to the service request.
See the service descriptions for the content of the response.
MSG Instruction Timeouts The default MSG instruction timeout is 30 seconds; the maximum MSG
timeout is approximately 35 minutes. Specify the MSG instruction
timeout by setting the appropriate member of the MSG tag:
• .UnconnectedTimeout member if the MSG is unconnected.
• .ConnectionRate and .TimeoutMultiplier if the MSG is connected.
The MSG timeout is determined by multiplying the ConnectionRate by
the TimeoutMultiplier. (Note: TimeoutMultiplier of 0 corresponds to
multiplier of 4, 1 corresponds to multiplier of 8, and so on).
Socket Instance Timeouts Each socket instance has an Inactivity Timeout (default of 5 minutes).
If a socket instance receives no service requests for the amount of
time specified by the Inactivity Timeout, the socket instance is
deleted. If you then try to use the socket instance, the MSG instruction
receive the error Class or instance not supported.
You can change the timeout by setting the Inactivity Timeout attribute
via the Set Attribute service.
See Socket Object Instance Attributes on page 159.
If you put the controller in Program mode and then back into Run
mode before existing socket instances time out, you can receive errors
when the program tries to create socket instances. Eventually the
socket instances time out and you can create more instances.
IMPORTANT
Make the value of the service Timeout parameter shorter than the MSG
instruction timeout, otherwise application data could be lost
IMPORTANT
Make sure the Inactivity Timeout is longer than the longest interval between
socket operations. If the Inactivity Timeout is too short, socket instances may
time out, resulting in MSG instruction errors.