摘要 |
A method of detecting communications errors by coding messages as pictures. A communications method useable to safely communicate a message or a signal from a first safety approved entity to a second safety approved entity via a third, non-safety approved entity including that each command is sent with the aid of a command message from the first to the second entity, an acknowledge message from the second to the first entity, and a go-ahead message from the first to the second entity.
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