Handling Broken PROFINET Connections

It is important in many industrial applications to detect faults quickly. One such fault is losing PROFINET I/O communication. PROFINET supports a configurable timeout value, which is expressed in terms of a multiple of the update time. The default multiplier is 3 for most IO Controllers. For example, for an update time of 16 ms and a timeout multiplier of 3, the connection timeout will be 3 x 16 ms or 48 ms.

When either the IO-Controller or IO-Device does not receive a packet from the other device for the timeout interval, it closes the connection and typically indicates this condition to the main program. The method of indicating this condition depends on the actual device. This topic describes the methods used by the RMC and STEP7.

Handling Broken I/O Connections in the RMC

The RMC has tags that indicate the state of the controlling connection. The user can use these registers to qualify whether certain operations in the User Programs can be done, or they can use these registers in the Program Triggers to respond to the change in state of the controlling connection. Notice that Controlling Connection can be either a PROFINET or EtherNet/IP IO connection.

Tag Name	Description
_Enet.CCStatus.Active	Controlling Connection Active This bit is set as long as a Controlling Connection is currently active. If the connection is closed or timed out, this bit will be cleared.
_Enet.CCStatus.TimedOut	Controlling Connection Timed Out This bit is not used for PROFINET.
_Enet.PLCStatus	Controlling PLC Status This register indicates the state of the controlling PLC. This register (DINT data type) can hold one of three values: Unknown (0), Run (1), and Program (2). The Unknown state applies whenever no controlling connection is active.

To find these registers when editing the Program Triggers or a User Program, use the Address Selection tree and browse to:

Controller > Communication Settings > Ethernet