CENTUM VP DCS Engineering Course

Chapter 1: CENTUM VP system architecture

CENTUM VP is Yokogawa's distributed control system (DCS). Like every DCS, it splits the job into stations that each do one thing well, linked by a redundant control network. Knowing what each station does, and where a signal travels, is the foundation for everything else in this course.

The main stations

• FCS (Field Control Station): the controller. It runs the control logic (function blocks, sequences, calculations) and talks to the field through I/O modules. In critical service, the CPU, power supplies and I/O buses are duplexed so a single failure does not stop control.
• HIS (Human Interface Station): the operator station, a Windows PC running the operator screens: graphics, faceplates, trends, alarms and messages.
• ENG (Engineering station): where the project database is built and changed. The engineering tools (System View and the builders) usually run on a dedicated PC, though an HIS can also carry the engineering functions.
• I/O: the analogue and digital input/output modules, mounted in nodes that connect back to the FCS over a redundant I/O bus. Modules are chosen per signal type: 4–20 mA with HART, thermocouple and RTD, digital input and output, pulse, and fieldbus communication modules.

The control network

The stations communicate over a dual-redundant control network (Vnet/IP on current systems). Every station has two network connections, called bus 1 and bus 2. If one bus fails, traffic continues on the other with no loss of control. Each station has a unique address made of a domain number and a station number. Getting this addressing plan right at the start of a project saves a lot of rework later.

Following one signal end to end

1. A pressure transmitter in the field sends 4–20 mA.
2. The signal lands on a marshalling terminal and is wired to a channel on an analogue input module.
3. The FCS reads the channel and passes it to a function block (for example, an indicator or a PID controller) that converts it to engineering units and checks alarm limits.
4. The HIS displays the block's value on a graphic and faceplate, and raises an alarm if a limit is crossed.
5. For a control loop, the PID output goes back through an analogue output module to a control valve.

Chapter 2: The engineering workflow

CENTUM VP engineering is database work: every station, I/O channel, function block and graphic is an entry in the project. A clear order of work keeps a large project manageable and makes changes traceable.

A typical order of work

1. Define the project and stations: create the project, then add each FCS and HIS with its domain and station number, matching the system architecture drawing.
2. Configure the I/O: define the nodes and modules in each FCS and allocate every channel to a tag, normally from the instrument index or I/O list.
3. Build the control logic: create the function blocks for each loop and wire them together in control drawings, then add sequences and calculations.
4. Build the operator interface: graphics, faceplate groups, trend groups, and the screen hierarchy operators will navigate.
5. Configure alarms and messages: priorities, alarm processing and operator guidance messages.
6. Test: check the logic against the design before any of it is downloaded to a live controller (covered in Chapter 9).

Why tag naming matters

Every function block has a tag name, and operators, engineers and maintenance staff will use those names for the life of the plant. Most projects have a tag naming convention, usually built from the plant area, the measured variable and the loop number, so that a name like 21PIC1005 tells you at a glance where the loop is and what it does. Agree the convention, and the rules for special cases (spares, calculated tags, sequence tags), before bulk engineering starts. Renaming hundreds of tags afterwards is slow and error-prone.

Bulk engineering

Large projects are rarely configured one block at a time. Typical loops are defined once as standard templates, and the I/O list and loop data are prepared in spreadsheets and imported. This makes the work faster and consistent: every flow loop is built the same way, so it behaves the same way and is tested the same way.

This is an independent course. It is not affiliated with, endorsed by or produced by Yokogawa. CENTUM and Vnet/IP are trademarks of Yokogawa Electric Corporation. For official documentation and certified training, contact Yokogawa.