Distrubuted control system training Part 3

PID Function Block Detail - Basic• Direct action The control action in which the manipulated output value MV increases as the process variable PV increases, or decreases as the process v

June 2012

Yokogawa Electric Corporation

Yokogawa Vietnam Co

Ltd Service Department

CENTUM VP ENGINEERING COURSE

Engineering Course

Schedule for the day :

Regulatory Control Function Sequence Control Function Laboratory Work

Day 3

Regulatory Control

Regulatory control blocks are functions blocks that perform control computation processing mainly on the analog input signals The calculated results are used for process monitoring and process control

Types of Regulatory Control

Input Indicator: PVI, PVI-DV Controller: PID, PI-HLD, PID BSW, ONOFF, PID TP,

PD MR, PI BLEND, PID STC Manual loader: MLD, MLD-SW, MC2, MC3 Signal selector: SS-H/M/L/SS Dual

Signal distributor: Split, FOUT

Function Block Diagram

Terminals

Data

Processing

Units

Input Processing

The function blocks are provided with various types of input processing methods

to convert the input signals for the calculation and arithmetic calculations

Signal read from

Output Processing

Output processing execute certain process to the values obtained from the control computation before output it

Output velocity Limiter: limits amount of change

bet current and previous out to avoid bumps

Output Limiter: limits

the MV tobe within

high and low limits

(MHI or MLO)

Output Tracking: forces the output value to match the value

of its output destination Output signal conversion: converts the result of

Preset Manipulated Output: upon an ext command, the block is put to manual and MV to a predetermined value

PID Block Terminal

PID Function Block

The PID Controller Block (PID) provides the most general control function to perform proportional-integral-derivative control based on the deviation of the process variable (PV) from the setpoint value (SV)

PID Function Block Detail - Basic

24 single-byte

characters

PID Function Block Detail - Basic

PID Function Block Detail - Basic

Scan period determines a period for the periodic execution of the function block.

Basic Scan

The basic scan is a standard scan period which is common to function blocks Default at 1s This cannot

be changed.

PID Function Block Detail - Basic

PID Function Block Detail - Basic

• Direct action The control action in which the manipulated output value (MV) increases as the process variable (PV) increases, or decreases as the process variable decreases.

PID Function Block Detail - Basic

Reverse direction Direct Control Action

PID Function Block Detail - Tag

PID Function Block Detail - Tag

When manipulating the important function blocks, other than the logged-on user, one more user’s confirmation may be required In this case, the confirmation may be performed on the Double Authenticated Confirmation dialog box.

In order to activate the double authentication for confirmation, [Double Authentication] setting on the Function Block Detail Builder must be set to [Yes] And the tag mark of the function block must be set as [Important].

There is no requirement that the user of [Name1] is superior to the user of [Name2] and vice versa Any users, excluding the user of [Name1] and the default users (OFFUSER/ONUSER/ENGUSER) can be act

as the user of [Name2] for double authentication.

PID Function Block Detail - Tag

The user-definable help dialog messages are treated as dialog names that may be specified as

HW0001 to HW9999.

PID Function Block Detail - Basic

MV may be displayed in actual quantity or in percentage (%).

If indicate actual quantity is selected, the value of MV will adopt the same engineering unit as

specified for PV and SV Otherwise, MV is converted into percentage

PID Function Block Detail - Tag

This mark indicates that the function block displayed on the instrument faceplate may be set to cascade mode However, the definition may be set AUTO to let system decide according to function block’s real

connection.

PID Function Block Detail - Basic

When the reverse scale display is specified, the low limit is displayed at the top of the scale and the high limit at the bottom of the scale.

PID Function Block Detail - Basic

In the standard display of a function block faceplate, the high limit displays at the top and the low limit displays at the bottom To designate the MV reverse-display may upside-down the standard display

PID Function Block Detail - Basic

This function displays indexes that show the permissible range of the manually

manipulated values at the normal operation

The manipulated output index is only available for Regulatory Control Blocks.

This function displays two indexes in the manipulated output value (MV) scale on the operation monitoring window of the operation and monitoring function These are called the manipulated output

indexes.

They can be used as manipulation guides in the manual mode, or as guides for verifying normal status in

PID Function Block Detail - Basic

PID Function Block Detail - Input

With “Holding PV,” when the data status of process variable (PV) becomes invalid, the last good

process variable is held.

PID Function Block Detail - Input

PID Function Block Detail - Alarm

IOP and

IOP-• Both input open alarms enabled

PID Function Block Detail - Alarm

Alarm Status

The priority for alarm display(Regulatory Control Blocks) is as follows:

OOP>IOP>IOP->HH>LL>HI>LO>DV+>DV->VEL+>VEL->MHI>MLO>CNF

PID Function Block Detail - Alarm

PID Function Block Detail - Alarm

PID Function Block Detail - Alarm

The alarm recovery point above or below the low/low-low or high/high-high limit.

Alarm Settings – HH, HI, LO, LL

Default HYS: 2% of PV Scale Span

e.g PV Scale High = 100, PV Scale Low = 0 HYS is set in Edit Function Block

Details of the control drawing

HYS: Hysteresis

PID Function Block Detail - Alarm

Single direction:

Alarm setpoint (VL) having a plus (+) sign, positive direction is monitored Alarm setpoint (VL) having a minus (-) sign, negative direction is monitored However, when VL=0, the velocity of both directions is monitored regardless

PID Function Block Detail - Alarm

The output open alarm check is a function that determines the data status received from the I/O module Based on the data status (OOP) received from the I/O module, an output open alarm (OOP) is activated

This alarm indicates that the control output line has been physically severed.

The output open alarm check is performed by the I/O module The function block receives the check results from the I/O module as a data status (OOP) and processes the activation or the restoration of the output open alarm The output open alarm is activated only in the function block that is directly

PID Function Block Detail - Alarm

Default is HL: Both

PID Function Block Detail - Alarm

Bad connection status alarm check may generate an alarm to indicate that the

connection is bad (CNF).

The bad connection status alarm check is a function that determines whether there is a faulty connection

to the function block or data at the I/O connection destination.

PID Function Block Detail - Alarm

The bad connection is judged as follows.

• The connected destination function block is in out of service (O/S) mode.

• The connection information is abnormal, and the data reference or data set cannot be performed.

PID Function Block Detail – Control Calculation

0: I-PD in AUT mode, PI-D in CAS mode or RCAS mode

1: I-PD 2: PI-D 3: PID 4: I-PD in AUT mode or RCAS mode, PI-D in CAS mode

PID Function Block

PID Function detail specification-Control Calculation

PID Function Block Detail – Output

The default is “Automatic Determination.”

When “Automatic Determination ” is selected, the engineering unit and scale range of the

PID Function Block Detail – Output

Default

PID Function Block

PID Function detail specification-Output

Rate of change

of mv PID

PID Function Block Detail - Connection

PID Function Block Detail - Others

Constants are preset tuning parameters Up to 1,024 alphanumeric characters can

be used for each constant.

Example of setting constants:

PID Function Block

Tuning Panel

Manual Loader with AUT/MAN Switch- MLD-SW

Manual Loader Block with Auto/Man SW (MLD-SW) may be applied as the lowest downstream block in the control loops that consist of multiple function blocks.

MLD output manipulated output value (MV) set from operation and monitoring function When in tracking mode (TRK) the tracking input signal received from the TIN terminal is output as manipulated output value (MV)

Motor Control Block MC-2/MC-3

The Motor Control Blocks MC-2 is applied to operate motor-driven pumps and motor-operated valves These blocks may be used to start

or stop motors from operation and monitoring functions or to control them automatically.

There 4 models of MC which behaves in different output manner

Two-position Motor control block MC-2

Enhanced two-position motor control block MC-2E

Three-position motor control block MC-3

Enhanced three-position motor control block MC-3E

Motor Control Block MC-2/MC-3

Motor Control Block MC-2E/MC-3E

MCx Block Data Item

Sample Connection of MC block

Types of Sequence Control Blocks

 Sequence Table block

 Logic Chart Block

 SFC Block

 Switch Instrument Blocks

 Sequence Element Blocks

Types of Sequence Control Blocks

 Sequence Table block

 ST16-Sequence Table Block

 ST16E-Rule Extension Block

 Logic Chart Block

 LC64-Logic Chart w/ 32 inputs, 32 output and 64 logic elements

 SFC Block

 _SFCSW- 3-Position Switch SFC Block

 _SFCPB- Pushbutton SFC Block

 _SFCAS – Analog SFC block

 Switch Instrument Blocks

 Sequence Element Blocks

 Valve Monitoring Block

Types of Sequence Control Blocks

 Switch Instrument Blocks

 SI-1 Switch Instrument Block w/1 input

 SI-2 Switch Instrument Block w/2 input

 SO-1Switch Instrument Block w/1 output

 SO-2Switch Instrument Block w/2 output

 SIO-11 Switch Instrument Block w/1 input, 1 output

 SIO-12 Switch Instrument Block w/1 input, 2 output

 SIO-21 Switch Instrument Block w/2 input, 1 output

 SIO-22 Switch Instrument Block w/2 input, 2 output

 SIO-12P Switch Instrument Block w/1 input, 2 one-shot outputs (pulse)

 SIO-12P Switch Instrument Block w/2 inputs, 2 one-shot outputs(pulse)

Types of Sequence Control Blocks

 Sequence Element Block

 TM Timer Block

 CTS Software Counter Block

 CTP Pulse Train Input Counter Block

 CI Code Input Block

 CO Code Output Block

 RL Relational Expression Block

 RS Resource Schedule Block

 Valve Monitoring Block

 VLVM Valve Monitoring Block

Sequence Control

Sequence Table Block (ST16) - 64 I/O

Signals , 32 rules (Up to 32 condition signals and 32 action signals for a total of 64 signals)

The conditions and operations are arranged in table format and specifies with operation

is performed by the combination of conditions This is suitable for the description of all sequences such as the parallel operation, interlock operation and sequence operation

Sequence Table Block

Sequence Table Display Area

Condition rules

Operation rules

The operator can monitor the control status of the sequence control block.

Function block

information

Signal comment/ Tag comment

Extended

Sequence Table - Stepless

Y : Yes

N : No

Red : Condition Satisfied

Cyan : Condition not satisfied

Red : Operation satisfied

Green : Operation not satisfied

Yellow : Not executing ( in the case of ST with a step label display) or ST block is in MAN or O/S mode.

Sequence Table - Stepless

Sequence Table - Step

Y : Yes

N : No

Red : Condition Satisfied

Cyan : Condition not satisfied

Red : Operation satisfied

Green : Operation not satisfied

Yellow : Not executing ( in the case of ST with a step label display) or ST block is in MAN or O/S mode.

The process control sequence of a phase-step process is divided into the smallest steps of the condition monitoring and operation, then these steps are executed one by one Only step label 00 and the rule corresponding to the current step number are subject to condition testing and operation

Only the step currently being executed is subject to condition testing

Sequence Table - Step

Sequence Table - Step

Sequence Table Process Timing

Process Timing:

• TE : Periodic start (T), output each time condition is satisfied (E)

• TC :Periodic start (T), output only when condition changes (C)

• OE :One-shot start (O), output each time condition is satisfied (E)

• OC : One-shot start (O), output only when condition changes (C)

• I : On initial cold start/restart (I)

• B : On initial cold start (B)

Periodic Execution (T)

The periodic execution means that the sequence control block is repeatedly executed in a preset

cycle.

One-Shot Execution (O)

In one-shot execution, sequence block is executed only once when it is invoked by other

function blocks.

Initial Execution/Restart Execution (I)

In initial execution/restart execution, the sequence block executes its process when the FCS

performs a cold start or a restart.

Restricted Initial Execution (B)

Sequence Control

Logic Chart Block (LC64)

In logic Chart Block, the conditions and operations are listed and the combination of conditions with the logic operators corresponding to the logic requirement many manipulate the operation signals This block can be used as the description of an interlock sequence control or logic chart

32 input and 32 output signal channels and it can handle 64 logic operators.

Logic Chart Display Area

Prints out logic chart

window currently displayed.

Calls up the dialog box for setting zoom levels.

The color of the line changes according to the progress of the process

A data value indicating the

completion status (complete:1,incomplete:0) is

When the output wiring for the input element is completed , it is displayed

in red , and in green when incomplete

Logic Chart Process Timing

Process Timing:

• TE : Periodic start (T), output each time condition is satisfied (E)

• OE :One-shot start (O), output each time condition is satisfied (E)

• I : On initial cold start/restart (I)

CALCU Function Block

The General-Purpose Calculation Block (CALCU) is a function block that executes predefined arbitrary calculation algorithms Calculation algorithms are defined using the general-purpose calculation expression description language.

Example script of CALCU FB:

CALCU Function Block

END OF PRESENTA

TION