Should a cut-off valve without a communication line be set to respond?
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Hello, experts. Recently we were troubleshooting a small complete set of equipment that includes a shut-off valve. The valve can be operated via the DCS, but there is no feedback regarding its operation status. The instruments indicated that no signal lines were connected to the valve, but after setting up an analog signal, feedback on the valve’s operation became available in the DCS. What’s going on here? How is this achieved? I hope some experts can help answer this.
It should be that a digital switch configuration was created, and then the wire carrying the feedback signal from the valve switch was connected
If there’s no feedback received, then it’s likely that fraud has taken place. If it is a pneumatic valve, then when the DO signal to the solenoid valve is 1, the display will show green to indicate that it is open; when DO is 0, the display will show red to indicate that it is closed. It’s quite easy to fake this, isn’t it? However, there are security risks, so it’s better to connect a feedback mechanism.
This post was last edited by GagaBeiCaiDao on 2017-7-27 at 14:14. Thank you for the reply. From what I’ve understood, a fake signal is generated; there’s only one solenoid valve responsible for controlling the valve. Is this fake signal generated based on whether the solenoid valve is energized or not? Thank you, moderator
What we do here is called \"tracking\" – you give a command and it gives a response, but of course it’s fake; the signal might not even be sent out
For this configuration, it’s sufficient to create a soft link; however, this approach is not recommended as it is a form of self-deception