5. sequence control - lc64

PT. Yokogawa IndonesiaWisma Aldiron Dirgantara 2nd floor, suite 202-209Jl. Jend. Gatot Subroto Kav.72 Jakarta 12780Phone : 021-799 0102, Fax : 021-799 0070

Training Services Center - SVDPrepared by:Arsianto Priandana

Logic Chart

PT YOKOGAWA INDONESIATraining Center – Technical Support Group

PT YOKOGAWA INDONESIATraining Center – Technical Support Group Page.1


CS3KEG-Sequence Control (LC64)


TYPES OF SEQUENCE CONTROL BLOCKS

The following function blocks are catagorized as sequence control blocks:

1.Sequence Table Blocks

2.Logic Chart Block

3.Sequential Function Chart Block

4.Switch Instrument Blocks

5.Sequence Element Blocks

6.Valve Monitoring Block




TYPES OF SEQUENCE CONTROL BLOCKS (2/2)

LOGIC CHART BLOCK

This function blocks performs interlock sequence control programmed in the expression of a logic chart diagram.

The following is the function block catagorized as logic chart:

• Logic Chart LC64Number of input elements: 32Number of output elements: 32Number of logic elements: 64

In a logic chart block, the conditions and operations are listed and the combination of conditions with the logic operatiors corresponding to the logic requirement may manipulate the operation signals. This block can be used as the description of an interlock sequence control or a logic chart.




LOGIC CHART BLOCK (LC64)





Logic chart function block can handle up to 32 input elements, 32 output elements and 64 logic elements/operators (however, logic element such as W.O, SR/Flip-Flop, or CMP is counted as 2 logic element operation.

(Input Signal) (Output Signal)





General Outlook Of A Logic ChartGeneral Outlook Of A Logic Chart

••Processing TimingProcessing TimingThere ara two processing timings:Start/Execution TimingIt refers to the timing at which control algorithms are executed when receiving input signals. Select one of the following type

- Periodic Execution (T)- One-Shot Processing (O)- Startup at Initial Cold Start/Restart of FCS (I)- Restricted Initial Execution (B)

Output TimingIt indicates the condition or behaviour of action signals in conjunction with the condition signalstatus change. For logic chart, the output timing is fixed to

- Output Each Time Conditions Are Satisfied (E)

••Scan PeriodScan PeriodSequence table with periodic execution type (T) is Sequence table with periodic execution type (T) is activated at defined scan period. activated at defined scan period. There are three types of scan periods:There are three types of scan periods:

-- Basic Scan (1 second Basic Scan (1 second –– fixed)fixed)-- Medium Speed Scan ( 200 & 500 milliseconds)Medium Speed Scan ( 200 & 500 milliseconds)

50, 100, 250 milliseconds are also applicable.50, 100, 250 milliseconds are also applicable.-- High Speed Scan (200 & 500 milliseconds)High Speed Scan (200 & 500 milliseconds)

50, 100, 250 milliseconds are also applicable.50, 100, 250 milliseconds are also applicable.





Start / Execution Timing

Periodic Execution (T)Periodic Execution (T)The periodic execution means that the sequence control block is repeatedly executed in a preset cycle.

OneOne--Shot Execution (O)Shot Execution (O)When execution timing of a function block is defined as one-shot type, the block is executed only when it is invoked by other function block. A one-shot function block can invoke another one-shot function block. However, such succession is limited to seven blocks. Invocation can only be initiated from the same FCS.

Invoking function block

One-shot type function block

Invocation signal

Sequence process execution

ACT.OFF

ACT.ON

Idle

Executing

One-Shot Processing Conceptual Diagram





Start / Execution Timing

Initial Execution/Restart Execution (I)Initial Execution/Restart Execution (I)In this execution type, the sequence block executes its process when the FCS performs a cold start or a restart.

Restricted Initial Execution (B)Restricted Initial Execution (B)In restricted initial execution, the sequence control block executes only when the FCS performs a cold start, not include restart.





Output Timing

Output Each Time Conditions Are Satisfied (E)Output Each Time Conditions Are Satisfied (E)The sequence table blocks output its operation/action signal every scan period as long as the judged conditions are satisfied.

Condition/input change

Action/output change

Action change/interuption is not possible as long as the condition remains satisfied.

False

True

False

True

“Output Each Time Conditions Are Satisfied” Conceptual Figure

Condition detection (false or true state)





Logic Elements




CASE





Switch Instrument Block Valve Monitoring Block (VLVM)

Timer Block (TM) Regulatory Control Blocks

Software Counter Block (CTS) Calculation Blocks

Pulse Train Input Counter Block (CTP) Faceplate Blocks

Code Input Block (CI) SFC Blocks

Code Output Block (CO) Unit Instrument Blocks

Relational Expression Block (RL) Sequence Table Blocks

Resource Scheduler Block (RS) Logic Chart Block

Condition Signal Description (Function Blocks and I/O Data)

Function blocks that can be processed in a sequence table are shown below.

I/O data that can be processed in a sequence table are shown below.

Processing I/O (Digital Input/Output)

Software I/O (Internal Switch, Annunciator, Global Switch)

Communication I/O




LABORATORY WORKS

Create a logic sequence from this control narrative:

Case Case 11

In a cascade loop, if the process variable of the master controller is High-High alarm then the slave controller mode will have to switch to MANUAL mode and the master controller mode will have to switch to AUTO mode.

The control mode of the slave controller cannot be changed until the alarm vanishes (process variable is in normal state).

TIC101

PIC101TT-101

PT-101 PV-101

Master Controller

Slave Controller

Condition : Alarm High-High

Action : Mode changes to Auto

Condition : Master controller alarm high-high

Action : Mode changes to ManualProhibit mode change if alarm is still




LABORATORY WORKS


Case Case 22

In a cascade loop, if the process variable of the master controller is High-High alarm then the slave controller mode will have to switch to MANUAL mode with its output drops to 2.5% MV and the master controller mode will have to switch to AUTO mode.

However, the operator is allowed to change the mode of slave controller to CASCADE or AUTO mode even tough the process variable is still in High-High alarm state.

TIC101

PIC101TT-101

PT-101 PV-101

Master Controller

Slave Controller




Action : Mode changes to ManualOutput (MV) drops to 2.5%Mode change is possible in spite of alarm




LABORATORY WORKS


Case 3Case 3

A tank level is monitored by LI102. It is also equipped with level switches LSL102 and LSH102.

If LSL102 is activated, SV102 will open that the tank will be refilled. Refilling process will stop when LSH102 is activated (SV102 closes).

Fuel Oil Make-Up

Furnace/Burner

LSH102

LSL102

I

SV102

SV103

TT--102102

P-102




LABORATORY WORKS


Case 4Case 4

If a tank level monitored by LI102 is in High alarm state for 10 seconds or longer, then the SV101 will open, and it remains open until LI102 Low level alarm is activated. (Note that the High alarm setting of LI102 is set above LSH102 setting & Low alarm setting is above LSL102). During normal operation, the Low alarm detection of LI102 is deactivated.

If the alarm last for less than 10 seconds, there is no change in SV101 action.

Fuel Oil Make-Up

Furnace/Burner

LSH102

LSL102

I

SV102

SV103SV101

Recirculation

LI102

I

TT--102102

P-102P-101Recirculation




LABORATORY WORKS


Case 5Case 5

Provide push buttons (operated from DCS, momentary action) so that the operator can open or close the SV102 at anytime, regardless the status of the level limit switches.

Fuel Oil Make-Up

Furnace/Burner

LSH102

LSL102

I

SV102

SV103SV101

Recirculation

LI102

I

IHS

102-BHS

102-AOPEN Command

CLOSE Command

TT--102102





LABORATORY WORKS

Buatlah sequence logic berdasarkan naratif kontrol berikut:

Case Case 11

Pada sebuah rangkaian cascade, apabila variabel proses (PV) kontrolermaster dalam keadaan alarm High-High maka mode dari kontroler slave akan berubah menjadi MANUAL dan mode dari kontroler master menjadiAUTO.

Mode kontroler slave tidak dapat dirubah selama variable proses masihdalam keadaan alarm High-High.

TIC101

PIC101TT-101

PT-101 PV-101

Master Controller

Slave Controller




Action : Mode changes to ManualProhibit mode change if alarm is still




LABORATORY WORKS


Case Case 22

Pada suatu rangkaian cascade, apabila variabel proses dari kontroler(PV) master dalam keadaan alarm High-High maka mode kontroler slave harus menjadi MANUAL dan outputnya (MV) turun menjadi 2.5% danmode kontroler master berubah menjadi AUTO.

Namun demikian, operator diijinkan untuk merubah mode dari kontrolerslave menjadi CASCADE atau AUTO meskipun variabel prosesnya masihdalam keadaan High-High Level.

TIC101

PIC101TT-101

PT-101 PV-101

Master Controller

Slave Controller




Action : Mode changes to ManualOutput (MV) drops to 2.5%Mode change is possible in spite of alarm




LABORATORY WORKS


Case 3Case 3

Level suatu tanki dimonitor oleh LI102. Tanki tersebut juga dilengkapidengan limit switch LSL102 dan LSH102.

Bila LSL102 teraktifkan, SV102 akan membuka untuk mengisi tanki. Pengisian akan berhenti bila LSH102 teraktifkan (SV102 menutup).

Fuel Oil Make-Up

Furnace/Burner

LSH102

LSL102

I

SV102

SV103

TT--102102

P-102




LABORATORY WORKS


Case 4Case 4

Apabila level tanki yang dimonitor oleh LI102 dalam keadaan alarm High selama 10 detik atau lebih, maka SV101 akan membuka dan tetap membuka sampai alarm Low level (LI102) teraktifkan (Catatan: setting untuk alarm High LI102 dibuat diatas LSH102 dan seting alarm Low dibuat di atas LSL102). Selama operasi normal, fasilitas alarm Low untuk LI102 tidak diaktifkan.

Apabila alarm High berlangsung kurang dari 10 detik, tidak ada perubahan operasiSV101.

Fuel Oil Make-Up

Furnace/Burner

LSH102

LSL102

I

SV102

SV103SV101

Recirculation

LI102

I

TT--102102





LABORATORY WORKS


Case 5Case 5

Berikan tombol operasi (dioperasikan dari DCS, bekerja sebagai pulse) sehingga operator dapat membuka atau menutup SV102 kapanpun, tanpa dipengaruhi oleh status limit switch pada saat itu.

Fuel Oil Make-Up

Furnace/Burner

LSH102

LSL102

I

SV102

SV103SV101

Recirculation

LI102

I

IHS

102-BHS

102-AOPEN Command

CLOSE Command

TT--102102





LABORATORY WORKS




PT. Yokogawa IndonesiaWisma Aldiron Dirgantara 2nd floor, suite 202-209

Jl. Jend. Gatot Subroto Kav.72 Jakarta 12780Phone : 021-799 0102, Fax : 021-799 0070

5. sequence control - lc64

Documents

logic chart block3

logic chart diagram

interlock sequence control

logic operatiors

logic requirement

logic elementsoperators

number of logic elements

sequence table blocks