PLC diagnostic buffer gains an additional source of information

During the commissioning of machines, sporadic and non-reproducible disturbances in PROFINET communication frequently occur. The root causes are often unclear, as the PLC diagnostic buffer provides only limited information. In practice, this often leads to the time-consuming replacement of connectors, cables, or network components without clearly identifying the actual cause. As a result, commissioning is significantly delayed.

Errors in the early commissioning phase are generally normal. However, problems arise when this phase is unexpectedly prolonged due to sporadic network issues. Systems that have already been tested may suddenly show irregular behavior: PROFINET devices drop out, are classified as defective, and replaced until the true cause—such as a faulty cable—is eventually identified. Troubleshooting consumes valuable time and prevents a structured software commissioning process.

The PLC typically monitors PROFINET communication in a binary manner: communication is either available or interrupted. Telegram gaps are tolerated up to a certain threshold and are not reported. Only when the watchdog time is exceeded is a fault triggered. As a result, an important intermediate state indicating emerging communication problems remains invisible.

This is where the PROFINET agent “Agent Blond” from Indu-Sol comes into play. Acting as a non-intrusive monitoring point, it detects telegram gaps on a per-device basis and makes this information available directly in the PLC via a GSDML file. The familiar diagnostic workflow remains unchanged, while additional network information becomes available for commissioning, service, and maintenance.

This enables targeted identification of sporadic network faults, reduced commissioning times, and a more reliable and transparent operation of the system over its entire lifecycle.