Determining Session Timer Values

It is important to choose your session time-out values correctly for your application. Values that are too low may cause sessions to be lost even though the remote node is running. Values that are too high may delay session problem notification. When considering what timer values to use, note that the iFIX WorkSpace may appear to be hung for up to the entire time-out period when sessions are lost. In production facilities, this delay may not give operators sufficient time to react to emergency situations.

For most applications, the default session time-out values are adequate. If you must modify the values to correct transient session losses, use this section to determine the correct values for your application.

iFIX uses the same session time-out values for every session. Changing the session timers affects sessions with every node in your iFIX network. In order to change the session timers, the changes must be made to every iFIX node.

You can also define remote node connection timers for each remote node defined in the SCU. The connection timers are identical to the session timers except that they affect communication with a particular remote node. Typically, the connection timers are used in place of the system-wide session timers when the connection to a remote node differs from the rest of the network. If you need to change these timers, make sure that the computers on both sides of the connection use the same timers.

Configurable session timers can be increased to solve the problems described at the beginning of this section. If you decide to change the values, it is recommended that you increase the Send and Receive values by 10 seconds and test to see if the problem is solved. If the problem persists, repeat the process until the problem is solved.

 

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