Based on safety requirement of Ethernet for plant automation (EPA) system, a new design scheme of embedded EPA bridge was presented with security mechanism across multi-layers in OSI model. Firstly, working principle and function framework of the embedded EPA bridge are given, then combining with EPA protocol and multitask scheduling mechanism of embedded operation system, the logical isolation
... [Show full abstract] method for message transmission of every micro-segment is adopted to realize the security performance of EPA field message transmission. Finally, the hardware implementation scheme of embedded EPA safety bridge is designed, and the software flows of port message sending or receiving and message information processing with security mechanism are given. Test results show that the EPA safety bridge can effectively guarantee the message transmission and the security of network communication in the field device layer, and it has less delay time for message transmission.