SINGLE CHANNEL BARGRAPH PROCESS INDICATOR series LI02

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SINGLE CHANNEL BARGRAPH PROCESS INDICATOR series LI02 Level and volume measurement in a tank

• 51 segment LED bargraph 0 to 100%, 5-digit LED display

• Analog input current 4 ÷^{20 mA}

• Programmable “Zero”, “Span” and decimal point position of the measuring level/volume range in physical units

• Programmable level – volume table of correspondence with maximum 20 points

• Modbus Аscii protocol over a galvanic isolated RS485 serial interface

• Programmable additive correction and digital filtering of measured level

• Two programmable relay outputs, according to the input signal (measured level)

• Galvanic isolated current output 4 ÷^{20 mA} programmable to level/volume

I. APPLICATION AND OPERATING PRINCIPLE

These process-indicators are designed for liquid level and volume measurement in a tank. The LED bargraph allows the measured value to be read from a distance with accuracy of approximately 2%. For better accuracy use the digital display. It is programmed to visualize the process physical quantities in real units.

The input signal is proportional (linear) to the tank level. The volume is calculated using the table of correspondence to the level. The maximum number of points is 20. Between the points the volume is calculated using a linear interpolation.

The beginning and the end of level/volume measuring range are programmed in physical units. The decimal point position is also programmable.

On switching of the device to the power supply the display and the bargraph enter to their basic operating mode. The options below to be visualized can be set via the keyboard:

1 Bargraph for level and display of static text “LEvEL”

2 Bargraph for level and display that indicates the measured level 3 Bargraph for volume and display of static text “ voL”

4 Bargraph for volume and display that indicates the computed volume

There are four LED on the front panel. LEDs А1 and А2 are for mode indication of the two relays. At closed

“normally open” contact the LED is lit (activated).

Via the keyboard is set which of the relays for physical units “l” or “m³ “ to be active.

An option for filtering of the input signal noise is included by setting of an exponential filter with coefficient 0.2 ÷ 1.0. For value of the coefficient equal to 1.0 there is no filtering of the input variable. For value of the coefficient equal to 0.2 there is maximal filtering of the input variable.

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II. OPERATION OF THE RELAYS

Two relays are embedded in the bargraph. They can be configured for the following action type:

^ОN/OFF control

Alarm relays.

In order to ensure proper operation the relays have to be assigned the following parameters:

tYPE Action type On/Off control or Alarm tP L Type of energizing limit High or Low SP Set point (reference)

HSt Hysteresis on activation t Time-delay on triggering

tErr Relay mode on error in measurement

The relays are controlled on the basis of measured level (process variable PV). The meaning of the various configurations is explained in the table below.

Alarm High Level Alarm Low Level

The relay switches on for PV > SP The relay switches on for PV< SP The relay switches off for PV ≤ SP – HSt The relay switches off for PV ≥ SP+ HSt

PV

Hysteresys Set Point

time Relay ON

Relay OFF

PV

time

Relay ON

Relay OFF

Control High Level Control Low Level

The relay switches on for PV ≤ SP – HSt The relay switches on for PV ≤ SP + HSt The relay switches off for PV> SP The relay switches off for PV< SP

PV

time

Relay ON Relay OFF

PV

Relay ON

Relay OFF

time

III. PRINCIPLE FOR COMPUTATION OF THE VOLUME

The bargraph has a current input, proportional to the measured level in the tank. The operator via the keyboard sets the decimal point and the range that corresponds to this input. This range is also used for scaling of the LED bargraph when visualization of level is concerned. Independently the decimal point and the range for the computed volume is set. The range for volume is also used for scaling of the LED bargraph when visualization of volume is concerned.

The correspondence level-volume table is set via the keyboard. The table consists of maximum 20 points.

Each point comprises two values – one for level and one for its corresponding volume. The number of points from 2 to 20 to be used is set via the keyboard. The points that fill in the table should be in ascending order, i.e. the first point in the table is for the lowest value. It is recommended that the first point in the table correspond to the beginning of the range for volume as well as the last point in the table corresponds to the end of the range for volume.

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When the measured level is between two points a linear interpolation between two adjacent points is used to compute the value.

IV. TECHNICAL SPECIFICATIONS

Power supply 230 V AC, 6 VA (24V on request)

Measuring inputs Current 4 ÷ 20mA

Basic accuracy < 0.1 % of the range ± 1 digit

Measuring range Programmable

Ambient temperature 0 . . . 23°С . . .55 °C

Resolution Function of the range

Digital display - LED bargraph

- five-digit LED display

- LED for operation mode visualization

Relay outputs Two SPDT relays 5А/250V

Serial communication RS 485

Galvanic isolated current output 4 ÷ 20 mA

Mounting For panel

Overall dimensions 72 х 144 х 100 mm , weight - 0.5 kg

Protection IP 30

V. CONNECTION DIAGRAM

A1A2

LLS02

9

4 5 6 7 8

1 2 3

Pt100

A

RS485

B Iout

+

13 14 12 11 10

20 19 18 17 16 15

+24V I/ U AGND 230V AC

Terminal No

Description

Power Supply

1,2, 3 Voltage supply - 230 V AС, < 6.0 VA;

Relays

4,5,6 Terminals 4 and 6 are the “normally open”

contact of relay 1

7,8,9 Terminals 7 and 9 are the “normally open”

contact of relay 2

Current Output

10,11 The current output is active, i.e. no need for external power supply.

Serial Communication – RS485 12,13,14 Terminals 12,13 are a twisted couple А

and В. А – „+”. Terminal 14 - Grounding (the screen of the cable)

Current Input 19,20 Terminal 20 – „-” , terminal 19 – „+”

18,20 Output Terminals 24VDC : 18 – „+ ”, 20 – “ - ”

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Attention:

The current input is passive and requires external power supply. The output leads of terminals 18 and 20 can be used as the external power supply needed.

Sample connections of the input to external power supply are shown in the figures below.

24VDC

PV 19

20

А 4-20mA Input

Power Supply Transmitter with

current output

А 4-20mA

24VDC

PV 19

20 Input

Power Supply

Transmitter with current output

Sample connection of the input with embedded power supply are shown in the figure below

PV 18

19

А 4-20mA Input

transmitter with current output

VI. PROGRAMMING

6.1. Basic mode of the indication

On switching of the device to voltage supply its indication settles in basic mode. The options to be visualized in this mode can be set via the keyboard according to the first table given in the present manual. In case of error in the input circuit (incorrect connection or out of order sensor) a message Err starts blinking on the display.

The same message appears also when the input variable is considerably above or below the range. The two LEDs A1 and A2 reflect the mode of the output relays. Lit (activated) LED means that the lead “normally open”

contact of the relay has been activated. Blinking LED means that at that moment the relay activation time- delay elapses.

In all modes of the indication the bargraph controls its outputs.

Pressing of the button MODE from the basic mode of the indication causes the message LEvEL to appear on the display.

The next pressing of the button MODE causes visualization of the measured level on the digital display and on the LED bargraph.

The next (third) pressing of MODE causes the message voL to appear.

The next (fourth) pressing of MODE causes visualization of the computed volume on the digital display and on the LED bargraph.

The fifth pressing of MODE causes the indication to return to the basic mode.

6.2. Parameters setting

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ALL MODES RELATED TO SETTING OF CONTROLLER’S PARAMETERS ARE ACCESSIBLE AFTER CORRECT ENTERING OF PASSWORD.

6.2.1. Entering of password

The password is entered by simultaneous pressing and releasing of the buttons ENT and MODE. Then on the indication appears 0000 and the needed password is entered via buttons “<“ and “^”. After that ENT is pressed and if the password is correctly entered the message PASS appears on the indication.

6.2.2. Menu structure

After a password has been correctly entered, the process-indicator enters a parameter setting mode. By pressing the button MODE all parameters for a given password are successively scanned and accessed.

Before each parameter various abbreviations remind of the corresponding parameter.

6.2.3. Editing a parameter

In all parameter setting modes a new value is assigned using the “<“and “^” buttons. The new value is saved only after pressing ENT. If the parameter has been changed with the “<“ and “^” buttons and ENT is pressed, the number on the display or the corresponding digit stops blinking and appears the new value. The transition to the next parameter is accomplished by pressing the button MODE. If before that the button ENT is not pressed, the value of the variable remains unchanged. After all parameters from a given menu have been assigned the display resumes its basic mode.

Depending on the various device configurations, in the menu dynamically appear or disappear various parameters. Below are shown all possible parameters which, depending on the current configuration, may be present or not in the menu.

6.3. Setting of decimal point, range for level, additive correction, filter, mode of indication

After simultaneous pressing of buttons ENT and MODE and entering of password 01111 an access to the following parameters is allowed:

№ Display Inscription

Meaning Measuring

units

Range 1 Pnt L Position of the decimal point. Changes with button “^”. -

2 rb L Beginning of the range for level Physical units

-9999

÷99999

3 rE L End of the range for level Physical

units

-9999

÷99999

4

dSPL

tLEvL Level and display of static text “LEvEL”

nLEvL Level and display, indicating the measured level

tvoL Volume and display of static text “ voL”

nvoL Volume and display, indicating the computed volume

- -

5 CorrL Additive correction to level Physical

units

-9999

÷99999 6

FiLt Coefficient of the digital exponential filter of the measurement. For value 1.0 no filtering takes place.

from 0.01 to 1.0

6.4. Setting of decimal point position, range for volume, configuring of the LED for the measuring units, number of points for the level-volume correspondence table

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Meaning Measuring

units

Range

1

i in Type of the current input 4-20 - 4÷20 mA

0-20 - 0÷20 mA

2 Pnt u Decimal point position for the volume Changes with button “^”.

3 rb u Beginning of the range for volume Physical

units

-9999

÷99999

4 rE u End of the range for volume Physical

units

-9999

÷99999 5 count Number of points for the level-volume correspondence

table

- 2÷20

6

LEd Which of the LEDs showing measuring units is to be lit LitrS - Litres

m3 – cubic meters

6.5. Setting of the level-volume correspondence table

Meaning Measuring

units

Range 1 L 1 Level of the first point

2 u 1 Volume that corresponds to L 1

3 …. ……

4 L x Level of point x

5 U x Volume that corresponds to L x Remark 1:

The number of points in this table is set with password 00004 for parameter count.

Remark 2:

In setting of the points if the button ENT is kept pressed the menu returns one parameter back.

6.6. Setting the parameters of the alarm relays

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After simultaneous pressing of buttons ENT and MODE and entering of password 00001 for relay 1 or password 00002 for relay 2 an access to the following parameters is allowed:

Meaning Measuring

units

Range

1 tYPE

The algorithm for the control of the relay nonE – the relay is not used

OnOf – On/Off algorithm AlAr – alarm relays

- -

2 tP L

Type of limit Lo- Low Hi - High

- -

3 SP Set point. Limit of activation Physical

units Range

4 hYSt Hysteresis Physical

units Range

5 t Time-delay for the activation of the relay seconds 0 – 200

6 tErr

The mode of the “normally open” contact of the relay in case of error in measurement:

oPEn - open CLSd - closed

6.7. Setting the parameters of the serial communication

Meaning Measuring

units

Range

1 Addr Device address - 1 ÷ 255

2

bAud Transmission/ reception rate ( changes with button ▲ ):

'9600' - 9600 bps '14400' - 14400 bps '19200' - 19200 bps

- -

3 bits Number of data bits - 7, 8

4 rS t Response time-delay milisec 5 ÷ 100

6.8. Parameters of the current output

№ Display Inscription Meaning Measuring units

1

Fol

L – the current output follows the measured level u – the current output follows the computed volume

-

2 out b Physical units which correspond to 4 mA of the current output

Function of the first parameter 3 out E Physical units which correspond to 20 mA of the

current output

Function of the first parameter

ONE-CHANNEL PROCESS INDICATOR WITH BARGRAPH

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LI02 series

SERIAL INTERFACE SPECIFICATION

1. Physical Layer

The implemented electrical interface conforms to EIA/TIA – 485 (RS485) standard. Two-wire serial configuration is implemented. All the devices must be connected on a trunk cable (bus configuration) constituted by 3 conductors. Two of these conductors form a balanced twisted pair, on witch a bi-directional data are transmitted. The third conductor is the shield of the twisted pair. This conductor is “common” circuit and must be connected directly to protective ground, preferably at one point only for the entire bus. Generally this point is to choose on the master device or on its Tap.

Each device may be connected:

- either directly on the trunk cable, forming a daisy-chain, - either on a passive Tap with a derivation cable.

In the second case, the derivation cable length must be less than 20m.

The typical connection diagram is shown on the next figure:

It is required to place a Line termination resistors (LT) near each of the ends of the bus with typical value of 360 Ohms (0.5W resistor).

The device also needs a line polarization resistors:

- a pull-up resistor to a 5V on B circuit,

- a pull-down resistor to the common circuit (0V) on A circuit.

The typical value for the polarization resistors is 1000 ohms.

A polarization of the pair must be implemented at one location for the whole serial bus. Generally this point is to choose on the master device or on its Tap.

The maximum number of devices on the serial line (including the master device) is 28.

The maximum length of the serial line is 1000m for communication speed of 9600 baud.

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Communication speed of 9600 baud is recommended for use, but 14400 or 19200 bauds are also possible.

2. Data Link Layer

The device conforms to a subset of the MODBUS over Serial Line specification V 1.0.

Supported are only MASTER requests in unicast mode. Broadcast requests are not implemented.

Only the ASCII transmission mode of characters is implemented. RTU transmission mode is not supported.

The format of each byte transmitted over the serial bus is:

1 start bit;

7 or 8 data bits, least significant bit sent first;

1 stop bit;

No parity bits are generated or checked.

3. Application Layer

The device conforms to a subset of the MODBUS Application Protocol Specification V 1.0.

The following three public functions are supported:

- Read Input Registers (function code 0x04) - Read Holding Registers (function code 0x03) - Write Single Register (function code 0x06)

The device will respond with ILLEGAL FUNCTION exception response on any other function request.

The maximum number of contiguous holding or input registers to read at once is five.

The following standard exception responses are implemented:

ILLEGAL FUNCTION (exception code 0x01) ILLEGAL DATA ADDRESS (exception code 0x02) ILLEGAL DATA VALUE (exception code 0x03)

The following user-defined exception responses are also implemented:

FAULT (exception code 0x80) – input circuit failure

VALUE UNDERFLOW (exception code 0x81) – the value is less than the lower range limit VALUE OVERFLOW (exception code 0x82) – the value exceeds the upper range limit Address space and variables

Every input register and every holding register is a 16-bit signed integer number, encoded using two’s complement notation.

Any attempt to address a non-existing register in the tables below will lead to ILLEGAL DATA ADDRESS exception response.

Any attempt to write data to a holding register outside the allowed range will lead to ILLEGAL DATA VALUE exception response.

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HOLDING REGISTERS Register

Number (hexadecimal)

Read/Write Range Description

0010 Decimal point position for Volume 0 … 5 0 – “000000.”

1 – “00000.0”

2 – “0000.00”

3 – “000.000”

4 – “00.0000”

5– “0.00000”

0015 Decimal point position for Level 0 … 5 0 – “000000.”

1 – “00000.0”

2 – “0000.00”

3 – “000.000”

4 – “00.0000”

5– “0.00000”

0026 Action type of relay 1 0 … 2 0 - nonE

1 - OnOf 2 - AlArm

0027 Type of the energizing limit for relay 1 ^{0 … 1} ^{0 - Low} 1 - High

0028 Relay 1 mode on error in measurement 0 … 1 0 - Open

1 - Closed

0029 Time-delay on triggering 0 … 200 seconds

0030 Set point for relay 1 (most significant byte) ^Range 0031 Set point for relay 1 (least significant byte) Range 0032 Hysteresis on activation for relay 1 (most

significant byte)

Range 0033 Hysteresis on activation for relay 1 (least

significant byte)

Range

0034 Action type of relay 2 0 … 2 0 - nonE

1 - OnOf 2 - AlArm

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0035 Type of the energizing limit for relay 2 0 … 1 0 - Low 1 - High 0036 Relay 2 mode on error in measurement ^{0 … 1} 0 - Open

1 - Closed

0037 Time-delay on triggering 0 … 200 seconds

0038 Set point for relay 2 (most significant byte) ^Range 0039 Set point for relay 2 (least significant byte) Range 0040 Hysteresis on activation for relay 2 (most

significant byte)

Range 0041 Hysteresis on activation for relay 2 (least

significant byte)

Range

0052 Measured value of Level (most significant byte)

0053 Measured value of Level (least significant byte)

0054 Measured value of Volume (most significant byte)

0055 Measured value of Volume (least significant byte)