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Classification and coding system

Classification and coding system to be applied

When designing an automated process control system, it is necessary to be guided by the rules for naming objects and variables, where each letter in the object name denotes some feature or function.

The rules for naming tags in APCS allow you to save a significant amount of time in the design and further maintenance of the object.

The designation of the technological position of the measured parameter is as follows:

the letter in the first position is a controlled parameter (discrete designation of letters):

T – temperature;

Р – pressure;

Pd – the pressure drop;

L – level;

С – consumption;

A – analysis, analyzer;

Q – gas contamination (concentration), a value characterizing the quality;

S – state, control of the shut-off valve solenoid;

I – electric motor current;

G – state, control of the technological unit - compressor;

N – state, control of the technological unit - pump;

V – state, control of the technological unit – fan;

Z – state, control of the technological unit - electric valve;

S – state, light board control;

B – state, furnace burner control;

I – manual impact;

letter in the second position - to clarify the measured value to describe the functional feature of the position:

E – sensitive element, sensor;

I – analog variable indication;

A – a sign of the input discrete signal of the DCS system, signaling;

S – a sign of the input signal of the ESD system;

С – parameter regulation (including positional);

Q – calculation of the total value of the parameter, integration;

Y – generated parameter according to logical conditions;

V – control valve, final actuating device of the control loop, discrete control of the technological unit;

T – device, terminal device of the measurement loop.

letter in third position:

A – system of special gas blowers (6505);

B – accounting and registration system (6506);

C – HVAC system (6509);

D – grouting system (6510);

E – extraction system (6520);

F – system of conditioned containers (6530);

G – system of substandard containers (6540);

H – chemically purified water supply system (6580);

I – system of dry reagents (6581);

J – hot water supply system (6582);

K – chilled water supply system (6583);

L – heating steam supply system (6584);

M – compressed air system (6585);

N – drinking water supply system (6587);

O – instrumentation system (6595);

letter in fourth position:

L – minimum value of the parameter, warning signal;

Н – maximum value of the parameter, warning signaling;

M – the state of the electric valve "jamming";

S – command "stop";

R – command "start";

O – open position, command to open;

C – closed position, command to close.

Dual modifiers H and HH and L and LL are used to designate the upper and lower levels of pre-alarm and alarm.

Numbers - the number of the technological position in accordance with the design document.

The alphanumeric combination corresponds to the reference designation of the technological unit.

Table 1 - Analog Signals

Letter designation

Description Example
Technological parameter

DCS/SIS AI LT Analog input signal from LTG100 level sensor

PT PT Analogue input signal from pressure sensor PTD101

ТТ Analog input unified temperature signal ТТN102

TE Non-standardized input temperature signal from primary transducers (thermocouple, resistance thermometer) TEA103

Control signal DCS/SIS AO LV, PV, TV Analog output control valve control, SAM LVF100

Based on the foregoing, the positions of instrumentation and instrumentation and the functions of the distributed control system and the emergency protection system are designated as follows:

Table 2 - Discrete signals
When assigning tags, the following conditions were accepted:

• the total number of alphanumeric characters in the tag name must not exceed 16;

• The use of punctuation marks and spaces to separate characters within a tag is not allowed.

Type (first letter of designation) Signal type

Code Description Example

Technological parameter DCS


TANN (pressure, temperature) high pre-alarm discrete input

Digital high alarm input (pressure, temperature)

Discrete low alarm input (pressure, temperature)

Discrete low level pre-alarm input (pressure, temperature)

Technological parameter PAZ DI

Digital high pre-alarm input (pressure, temperature, differential pressure)


TSH (Pressure, Temperature, Differential Pressure, Vibration) High Alarm Digital Input


Discrete low alarm input (pressure, temperature, differential pressure)


Discrete low level pre-alarm input (pressure, temperature, current, differential pressure)

Электрозадвижка (Z)
ZSC Gate closed status ZSC161

ZSO State valve "open" ZS0161

ZSM Locked valve status ZSM161

ZVC Close valve command ZVC161

ZVO Open valve command ZV0161 ZV0161

ZVS Stop command ZVS161 ZVS161

When assigning tags, the following conditions were accepted:

the total number of alphanumeric characters in the tag name should not exceed 16;

the use of punctuation marks and spaces to separate characters within a tag is not allowed.

2 Coding of function blocks in the database

When specifying a tag in the database, a set of tag characteristics is set, in accordance with which the following is determined: tag type, protection code, tag description (up to 16 characters), method of accumulation and presentation in the historical database, data source. Depending on the tag type, additional tag characteristics can be set, such as: minimum and maximum values, scaling and offset, "On" and "Off" labels, and others. The characteristics of the tag refer to regulatory and reference information, and its current value is operational information.

Table 3 shows examples of letter designation of the main types of process parameters.

Table 3

Tag letter Description Note

ТIOххххх Software block for controlling the process temperature parameter (TP) Function block (PID)

TIxxxxx Temperature parameter indication software block (TP) Function block (PVI)

TYxxxxx Calculated Temperature Value (TC) Program Block Function Block (CALCU)
TDCxxxxx Программный блок управления вычисленной разницей температур (ТП) Функциональный блок(PID)
FICxxxxx Flow Rate Control (FC) Software Block Function Block (PID)

FIxxxxx Program flow indication block (FC) Function block (CALCU)

FYxxxxx Program Flow Correction Block (TC) Function Block (PID)

LICxxxxx Software level control block (TP) Function block (PVI)

LIxxxxx Software level indication block (TL) Function block (CALCU)

PICxxxxx Software pressure control block (TP) Function block (PID)

PIxxxxx Software pressure indication block (TP) Function block (PVI)

QICxxxxx Furnace Thermal Load Control Software Function Block (PID)

QYxxxxx Furnace Heat Load Calculation Software Block Function Block (CALCU)

AIxxxxx Program block for indicating the value of a variable (V) transferred from the analyzer Function block (PVI)

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