BNI0098 discrepancy timer setting

The default settings of BNI0098 as they appear in the GSD for Profinet BNI master modules may not be correct to work with a selection of Safety field devices.

Incorrect settings may lead to safety passivation which does not specify what is the root cause of the issue. If the physical connections and functionality of the end devices are not of concern, the next point to look at is the discrepancy and input delay time settings of BNI0098.

Another indicator of the discrepancy or input delay time incorrect setting is the error 27 showing up in the BNI0098 Error Log.

Sometimes the system may work without any issues for a long period of time, but in most cases such stability is down to the safety devices not being used actively. Alternatively, the errors may happen on the daily or even hourly basis if the machine is in constant use.

Most Safety devices have got a response or delay time specified in their documentation. Both values can be used as a reference for the discrepancy timer setting of BNI0098.

Here are some examples of product documentation for a magnetically coded safety switch:

...and a safety touch button:

The ports of the BNI0098 have to have the discrepancy timer of at least 150 and 20 ms respectively.

After the discrepancy timer correction, the safety passivation does not occur on any Safety channel. The customer may also decide to increase the input delay timer at their own discretion.   Balluff may not advise the input delay timer value as it's directly affecting the safety rating of the system and should be checked with the design engineers of the system in question.

In addition, due to prioritized structure of errors of the BNI0098 some lower-level errors may only be detected after the described timer configuration is rectified. In the actual application, the occasional wire break error could only be detected after the passivation issues have been resolved.