QUESTION:
If one master fails in my multimaster system, are the other systems still able to communicate?

ANSWER:
In your network there are multiple masters that each have access to multiple slaves. If one master fails, e.g. through power failure or another technical defect, then the following must be noted:
If the failure of one master in a multimaster system is due to a hardware fault, then under circumstances the complete network can be put out of action through a short-circuit on the bus line. In this case the fault must be cleared and the defective master removed from the network. If the failure of the master has no direct effect on the electrical properties (e.g. CP in STOP mode or power failure of the complete station), then the network can continue working.

If the master concerned is the last bus user in the bus network, then the following must be noted for PROFIBUS/MPI:
The open PROFIBUS line end must always have an active terminating element, i.e. one to which power is applied. This prevents reflections (noise or interference signals through periodic and/or random deviations) on the bus line. This is the only way for the other stations to be able to continue with unimpaired data communications. You can use the terminator that is included in the PROFIBUS connectors, but this has the disadvantage that if the complete station fails (e.g. through power supply failure), the network terminator is also lost. Then your complete network fails. It is better to use an external terminator (MLFB: 6ES7972-0DA00-0AA0), that is independent of the power supply of the automation systems.

Note:
You do not need a terminator for Industrial Ethernet.

If the failed master does not cause a bus short-circuit, then it does not need to be isolated from the bus. The communication of the intact master stations with their slaves is not affected.
The other masters can continue to have data communications with their slaves. The total cycle time is even shortened by the bus access time of the failed master.

Keywords:
Network nodes