Meaning of DCS Symbols in Yokogawa VP System (1)

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The manufacturers of DCS systems used in the petrochemical industry include Yokogawa, Honeywell, Zhejiang University Control System, Emerson, Hollyland, FOXBORO, etc. In some olefin plants, the Japanese Yokogawa VP system is employed. In DCS systems, there are many abbreviations, and for many frontline operators, it is not clear what these symbols and parameters mean. This article takes the TUN of a control loop in the DCS of the Yokogawa VP system for an olefin project as an example. TUNING view: The TUNING view displays the detailed control status of an individual functional block. This view can be used to monitor and change the setting parameters. It is also used to adjust various setpoints and control parameters, as well as to add and remove operation markers. When a function block is created in the function block overview editing window, its tuning view is generated automatically. Modifying different parameters in the tuning view requires different levels of permission; these permissions can be switched using keys via the user login interface or the operator keyboard in order to make parameter changes. Hard copy: This button outputs an image of the tuning view currently displayed. :The Acknowledge button is used to confirm the alarms generated by the displayed function block. :Reserve: When this button is pressed, trend data collection continues even if the trend window is closed ； When this tuning window is opened next time, this tuning trend will be displayed. This button is used when the trend display is active. :Stop/Resume: When this button is pressed, the setpoint trend display is paused. When this button is rebounded, it returns to its initial state, with updates being displayed again. When this button returns to its initial state, the setting trend display resumes to the current time. Note that data acquisition continues even when the display is turned off. :Reduce/Enlarge Time A*s: Click this button to zoom in or out on the trend chart along the time axis (horizontal direction), using the right edge of the image as a reference point. This button is used when displaying the tuning trend. This timeline range is 00:06:43→00:13:26→00:26:52→00:53:44. Click Reduce/Enlarge DataA* to shrink or expand the display range of the data axes related to the trend chart, provided that the trend chart is displayed in analog format. This button is used when displaying the tuning trend. This data axis scaling range: 100%→50%→20%→10%. For AOF, clicking this button changes the function block mode to AOF mode, thereby disabling alarms. When this button is clicked, a dialog box appears to prompt the operator for confirmation. To return to the original state, click this button again. This button appears in the displayed tuning diagram only when the function block supports AOF mode. :CAL: Click this button to change the data status to corrected. When this button is clicked, a dialog box appears to prompt the operator for confirmation. To return to the original state, click this button again. This button appears only in the tuning diagram displayed when the function block supports the correction mode. :Operation: This button opens the dialog box for specifying operation tags. In the operation tag dialog box, it is possible to define the instrument panel operation tags to be displayed on the tuning diagram. file:///C:/Users/15896/AppData/Local/Temp/msohtmlclip1/01/clip_image011.png:Control Drawing Click this button to display the control chart. :Raw data: This button opens a dialog box displaying “RAW” data. This button is only displayed for function blocks with “RAW” data items. Note: The PRD function (not available in this module); this button is accessible in the setting view displayed when the functional block supports direct control of the PRD mode via the main circuit. MODE: Mode. SH: PV scale high limit – the upper limit of the scale. SL: PV scale low limit – the lower limit of the scale. PV: Process variable – the value measured on-site. SV: Setpoint value – the desired value. MV: Manipulated output value – the actual output value. DV: Control deviation value – the difference between the actual value and the setpoint. SUM: Totalizer value – the cumulative value. OPHI: Output high-limit index. OPLO: Output low-limit index. ALRM: Alarm status. HH: High-high limit alarm setpoint – the setpoint for high-high limit alarms. PH: High-limit alarm setpoint – the setpoint for high-limit alarms. PL: Low-limit alarm setpoint – the setpoint for low-limit alarms. LL: Low-low limit alarm setpoint – the setpoint for low-low limit alarms. VL: Velocity alarm setpoint – the setpoint for velocity-related alarms. DL: Deviation alarm setpoint – the setpoint for deviation-related alarms. SVH: Setpoint high limit – the upper limit of the setpoint. SVL: Setpoint low limit – the lower limit of the setpoint. STC: STC operation mode selection switch – switch for selecting the STC operation mode. TR: Process 95% response time – the time required for the process to respond at 95%. BSTS: Module status. MH: Manipulated variable high-limit setpoint – the upper limit for the manipulated variable. ML: Manipulated variable low-limit setpoint – the lower limit for the manipulated variable. P: Proportional band. I: Integral time. D: Derivative time. GW: Gap width – the width of the gap. DB: Deadband – the range within which no action is taken. CK: Compensation gain – the gain used for compensation. CB: Compensation bias – the bias value used for compensation. PIDC: PID update ratio coefficient – the coefficient related to PID updates. 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