Technical Manual
LioN-Link PROFINET
Subject to change without notice!
Version 1.2 / August 2014
Page 27 of 30
9.
Alarm and error messages of the BusHead
If the BusHead detects an error condition, then it triggers an alarm message. The BusHead supports diagnostics alarms.
Diagnostics alarms are released in case of periphery faults, like overload, short circuit and broken wire.
If an I/O-module at a LioN-Link line is removed or if it is no longer accessible (module breakdown, connection disturbed,
“pulling“ the module), an alarm is triggered also. This alarm is called a pull alarm.
An alarm is triggered with a coming event (e.g. sensor short circuit), as well as a going event.
The evaluation of the alarms is carried out in dependence of the used PROFINET IO controller.
9.1.
Evaluation of alarms in
STEP7
In
STEP7
the processing of the user program is interrupted by triggering a diagnostics alarm and a diagnostics organization
block is called. The following organization blocks are called.
Cause of the alarm
OB-call
Periphery fault (short circuit, overload,
broken wire, low voltage at I/O-module)
OB 82
Pulling an I/O-module, I/O-module no
longer accessible
OB 83
Complete breakdown of the system
OB 86
Based on the called OBs and their start information, first information about the cause of the fault and kind of the fault are
delivered already. Detailed information about the fault can be obtained in the fault OB by calling the SFB 54 RALRM (Receive
additional alarm information). The SFB 54 therefore has to be called in every fault OB.
If the called fault OB is not available in the PLC, the PLC changes to the operation mode STOP.
9.1.
Reaction of the BusHead to a module breakdown („pull “ alarm)
If an I/O-module on the LioN-Link line fails due to an interruption of the communication (removing the I/O-module,
disconnection of the link connections, broken wire, I/O-module fault), the BusHead generates a “Pull-alarm“. At the BusHead
itself this condition is indicated by the red “DIA”-indicator flashing up.
The “pull“-alarm immediately starts the execution of the OB 83 in the
STEP 7
PLC. Within the OB 83 more information can be
evaluated by calling the SFB 54 RALRM.
After the BusHead properly triggered the „pull“-alarm, the BusHead periodically tries to restart the incomplete LioN-Link line
again. The attempt to restart the affected line is indicated by an alternating red and green lighting-up of the indicators S1
and/or S2 at the two link lines on the BusHead. This condition is maintained as long as both Link lines are completed by the
correct I/O-modules at the configured positions.
Important note!
During a configuration error (missing or incorrect I/O-modules) in a LioN-Link line the BusHead does
not disconnect from the network, but returns again to the cyclic data exchange after the error is
resolved. This behaviour applies during operation but also after restarting the LioN-Link system.
