Is the control valve an AI point or an AO point?
Thread Content
When DCS control is set to manual, it adjusts the valve opening; this should be an AO point. If DCS control is set to automatic, the valve opening can be displayed – isn’t that an AI point then? Or when it’s in automatic mode, is the valve opening not based on feedback from the field, but rather determined by the automatic control system through measurements such as flow rate changes? Is this the correct way to understand it? My expression might not be very professional; it’s roughly what I mean
Yes, when it operates in automatic mode, it is still the DCS that sends signals to the control valve; unless the control valve has an analog position feedback system, in which case what is sent to the DCS is in AI format
Conventional pneumatic control valves are AO; electric control valves equipped with a valve position transmitter come with AI/AO
The valve positioner has an input signal and a feedback signal; the positioner’s input signal corresponds to the AO of the DCS, while the feedback signal is connected to the DCS and corresponds to AI
Can a two-wire system locator be connected to both AI cards and AO cards at the same time? 、
Taking the Siemens positioner 6DR5210-0NN01-0AA0 as an example, the digit 1 in 0NN01 represents the feedback signal of the positioner (4-20mA)
It is generally determined based on the process variables being adjusted
The DCS is set to automatic mode; the valve opening displayed is the output value of AO, while the valve opening reported back by the valve positioner is the AI value.
The control points of the DCS should not be determined based on the DCS display, but rather according to the list of instrument equipment.
No, if it’s a 2-wire system, then AO needs to be connected