QUESTION:

How can short-term errors / releases of safety components be recognized? The system remains at a standstill but it is not known which component has released.

ANSWER:

During the troubleshooting of sporadic releases, functions “diagnostics hold” respectively “local acknowledgment” should be activated. Those are the general methods to localize the cause.

With this information, the corresponding safety components can be examined more closely and therefore necessary measures regarding mechanics, EMV or system construction can be initiated.

If necessary, the analyzer AS-Interface 3RK1904-3AB01 could be used. The AS-i Analyzer is used for testing AS-Interface networks. Troubleshooting is made systematic and permanent monitoring facilitated.
This device is able to detect errors during the installation such as loose contacts or EMV problems.
The easy-to-use software makes it possible to check the quality of whole systems even without detailed technical knowledge about AS-Interface. The analyzer furthermore makes possible documentation of commissioning and services by the simple generation of test reports for the recordings made.
Detailed diagnostics are made possible for advanced AS-Interface users by means of trigger functions. 

QUESTION:

Can short-term faults on the Safety at Work bus be suppressed with a time delay (i.e. does the monitor go into error mode if the release is shorter than the time delay, or does it remain switched on)?

ANSWER:

In this case, it depends on the type of error. Incorrect transferred Code sequences can not be suppressed generally. Short-term contact openings (for example because of vibration) may be suppressed by a time function element (switch-off delay), but results in a delayed switch-off also in the error-free operation. This switch-off delay would neither detect the relevant and safe AS-i-Slave in case of a failure of the AS-i-Bus (during the waiting time).
Those measures extend the total response time and are normally incompatible with the safety requirement.

Therefore, we recommend to remove the cause and not to evade the reaction.

QUESTION:

How does one connect two AS-Interface bus systems in which Safety at Work is used?

ANSWER:

You will find a sketch of the principle attached which shows you how you can connect two AS-Interface bus systems in which Safety at Work is used.

For the coupling of category 4 secure signals, an additional monitor and a secure module are needed per AS-Interface bus.

The monitors which are used for coupling (1.1 and 2.1) should be programmed with automatic start.
The monitors which can be used for switching-off (1.2 and 2.2) can be programmed with each of the start blocks, according to request.

With teaching, the coupling monitors must first be taught and enabled.

If only one channel is needed for switching off, then the second channel can also use the function of the second monitor.

With teaching, all secure modules must have closed contacts.

This can only be done by implementing with 2 monitors when both K45F are bridged (e.g. with an input jumper).

You will find an example program attached of what the realization could look like.
 

44234_e.zip ( 20 KB )