通过使用类似IO-Link的网络，一些相同的功能正在回归传统的安全继电器。每个安全设备都驻留在一个网络上，有自己独特的地址。
特定网络上的所有设备(通常每个安全继电器有两个可能的网络)都是菊花链式的，类似于更传统的安全继电器电路，但是网络上的每个设备或节点向安全继电器提供与该特定节点设备的状态和性能相关的附加信息。
最后，许多制造商提供安全控制器嵌入或完全取代传统PLC或PAC的产品，这是一个具有安全控制器和PLC/PAC所有优点的编程环境。
PLC机架中的I/O模块可以是安全或常规I/O，或者是两者的组合。另一件值得关注的事情是本质安全无线安全前景的出现。现在，对于我这样的老前辈来说，这个概念是一个很难消化的东西。如果在各种安全设备和安全控制器或继电器之间没有物理连接，怎么可能安全呢？
对安全的持续改进都是为了保护我们的人民，这一趋势没有丝毫减缓的迹象。绝对值得再看一眼。
By using networks like IO-Link, some of the same functions are returning to traditional safety relays. Each security device resides on a network with its own unique address.
All devices on a particular network (typically there are two possible networks for each safety relay) are Daisy chained, similar to a more traditional safety relay circuit, but each device or node on the network provides additional information to the safety relay related to the status and performance of that particular node device.
Finally, many manufacturers offer products that embed or completely replace traditional PLCS or PACs with safety controllers, which is a programming environment with all the benefits of a safety controller and PLC/PAC.
The I/O modules in the PLC rack can be either safe or regular I/O, or a combination of both. Another thing to watch is the emergence of intrinsically secure wireless security prospects. Now, for old-timers like me, this concept is a hard thing to digest. If there is no physical connection between the various safety devices and the safety controllers or relays, how can safety be possible?
Continuous improvements in security are all about protecting our people, and this trend shows no signs of slowing down. It's definitely worth a second look.
