Abstract: Wireless communication is a key issue in many industrial and research areas. On one hand cables are not necessary anymore, and this reduces costs while it is getting much more flexible and information can be selected from any device. On the other hand, safety and especially security are becoming even more important as data can be read by everyone and can be more easily perturbed or intentionally falsified. This article defines protocols that changes its safety attributes according to the continually calculated probability of error per hour value. A grey (gray) channel is defined that is not ignoring any information from the communication channel (black-channel) and uses the observed information to adapt the safety attributes. The protocols use short data-lengths and several different cyclic redundancy checks (CRCs) which are changed depending on the current safety integrity level, the observed channel characteristics and the amount of data to be sent.

Keywords: Adaptive communication protocol, Probability of failure on demand, Safety integrity level, Black-channel, Grey-channel.

.__________________________________________________________________________________________