In what situations is it necessary for a hard-link signal to be used for interlock control?
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This post was last edited by zhaohh3211 on 2016-8-11 at 13:42. Under what circumstances is it necessary to use a hard link signal for interlock control? 1. During the DCS configuration process, data is definitely retrieved through communication, such as using the ModBus protocol; such data cannot be used for control purposes. Only data obtained via 4-20mA DC can be used for control. Is that the case? Some people say that signals used for interlock control must be transmitted through hardwired connections, specifically via 4-20mA DC signals. I believe that DP and FF buses are fieldbuses used for data communication; the communication lines are also hardwired, and they have already replaced 4-20mA DC signals in connecting field instruments to DCS controllers. 2. Please also discuss what would be the appropriate approach Let’s discuss what is used for interlocking and control, and when to use 4-20mA DC and when to use communication Please share your opinions; talk about whatever comes to mind. People in design institutes focus on standards, and it’s also fine to follow certain specifications or rules
Signals used for regulation and interlocking should generally be hard-wired signals, as this provides greater reliability. Communication signals involve many uncertainties, such as communication interruptions and slow communication speeds. In fact, the speeds of field buses like DP and FF are not sufficient to meet the requirements for fast, real-time regulation; various articles have analyzed this issue. Another example is signal quality assessment; if communication diagnosis is not done properly, it becomes difficult to determine the issue when a communication failure occurs, which increases the risk of errors in adjustments or interlocks. With hard-wired signals, it is relatively easy to assess signal quality issues and avoid misoperations.
This post was last edited by ccbaby123 on 2016-8-13 19:08. Buses can be used for interlocking, but Modbus cannot. Your first point is also incorrect; the vast majority of DCs do not use Modbus to collect data. Note that it’s not necessary; it doesn’t mean the feature is absent
The main issue is the unreliable communication connection; interruptions in communication or slow speeds can result in the controls and interlocks not functioning or operating with delays. Therefore, communication signals are generally used for display, while wired connections are used for controlling interlocks
Like it – clear viewpoints and sound analysis