Which products are affected?
8200motec / vector, starttec and Drive PLC in combination with the fieldbus function module CAN.
What happens?
Basically the internal supply voltage (terminal 20) can be used for activating the digital inputs and supplying the digital outputs. The signals being supplied by the internal voltage source cannot be processed if the error described above has occurred. This may affect the controller enable function for instance.
Moreover, the CAN communication may be interrupted.
When does the problem occur?
When heating the modules to temperatures >50 °C (our value from experience) the supply voltage at terminal 20 can drop or collapse.
Possible diagnostics?
If the measured voltage level between terminal 20 and terminal 7 (GND) is < 17.5 V and if it is > 17.5 V again after cooling down the module used this is a hint that the problem described before may have occurred.
The voltage drop at terminal 20 is favoured by a higher ambient temperature and current load at the same terminal.
Short-term measures/recommendations?
Use the external voltage supply instead of the internal voltage source (terminal 20). As a result the DC-DC converter is unloaded and a repeated temperature-dependent failure becomes improbable.
Or exchange the modules for the following revised and corrected versions.
Evaluation:
Among other things, the controller enable function is deactivated due to the collapse of the supply voltage and as a result the controller is inhibited.
By unloading terminal 20 the voltage level > 17.5 V can reset automatically.
