[Discussion Thread] Which specification states that interlocking signals must use hard wires?
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This post was last edited by Xiao Fu fu on 2024-9-27 at 14:20. [Discussion Thread] Which specification states that interlocking signals must use hard wires? What is currently known (as stated in clause 9.6 of SH 3018-2003, which specifies that safety instrument systems should use 4-20mA DC analog signals, and not fieldbuses, HART, or other type of communication signals) outlines the use of interlock signals. But are there any other standards or national regulations that address this issue as well? Discussion is welcome!
This post was last edited by hanhaigang128 on 2024-9-27 at 16:21. Clause 6.1.3 of HG/T 22820-2024, \"Design Code for Chemical Process Safety Instrumentation Systems\", which will come into effect on October 1: Measurement instruments should preferably use analog output signals; however, instruments with digital output signals can also be used. Measurement instruments shall not use fieldbus signals or signals from other communication protocols as input signals for safety instrument functions, nor shall they use wireless signals as input signals for such functions.
National standard specifications do address the use of interlocking signals. Generally, for the transmission of interlock signals, especially in safety instrumented systems, hardwired connections are recommended to ensure the safety and reliability of the system. This helps to minimize the likelihood of interference to the signal during transmission. For specific specifications, refer to relevant national standards such as the \"Design Specifications for Industrial Process Measurement and Control Systems\". .
In practical applications, it has been found that signal transmission delays caused by bus communication interference in chemical processing environments are quite significant, and this constitutes a factor contributing to its unreliability.
No mandatory standard requires that interlocks must use hardwired connections; it’s simply that engineers choose the most conservative approach when implementing them. The opposite of hard wiring is communication; foreigners often use the term \"communication\". Profibus has a very wide range of applications, but in China Modbus 485 is the most commonly used standard, and it seems less reliable... That’s why hard wiring is generally used for signals, especially for interlock signals/
Yes, after all, automation serves production with the goal of ensuring stability in production
That’s right; unstable production will result in evaluations~!
GB50770 mentions hardwired connections only once