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Loadcell Loadcell Help Rev: 17/06/04

Table Of Contents Loadcell ........................................................................................................................................... 1

Loadcell Quickstart................................................................................................................... 1 FB Operations .......................................................................................................................... 1

Loadcell Help Rev: 17/06/04....................................................................................................... 2 Loadcell Quickstart................................................................................................................... 2 FB Operations .......................................................................................................................... 2

Loadcell Hardware Configuration ................................................................................................ 3 Configuring a Loadcell.............................................................................................................. 3

Loadcell: Configuration ................................................................................................................ 4 Scan ............................................................................................................................................. 6 Calibration.................................................................................................................................... 6

Calibrating Points ..................................................................................................................... 6 Calibrate Point FB .................................................................................................................... 7 Save Calibration ....................................................................................................................... 8

Tare & Zero.................................................................................................................................. 8 Tare & Zero .............................................................................................................................. 9

Setup.......................................................................................................................................... 10 Motion Band ........................................................................................................................... 10 Filter and Rounding ................................................................................................................ 11 Auto Zero Tracking................................................................................................................. 12

Loadcell Operands & Status Messages..................................................................................... 12 Loadcell Hardware Status Messages (Hardware Configuration) ........................................... 14

Advanced Loadcell Functions........................................................................................................ 17 Advanced Functions .................................................................................................................. 17 Advanced Functions .................................................................................................................. 17 Advanced-Calibration................................................................................................................. 17

Edit Calibration Point: value via operand or constant ............................................................ 17 Read Calibration Point ........................................................................................................... 17 Delete Calibration Point.......................................................................................................... 18 Clear Calibration..................................................................................................................... 18 Enable/Disable all other load cells ......................................................................................... 19

Setpoint ...................................................................................................................................... 19 Set and Activate Setpoint ....................................................................................................... 20 Deactivate Setpoint ................................................................................................................ 21

Change Representation Mode................................................................................................... 22 Reset Net Min/Max Values ........................................................................................................ 22 Change Excitation Mode............................................................................................................ 22 Input Range................................................................................................................................ 22

Set Gain FB............................................................................................................................ 22 Set Offset................................................................................................................................ 23 Read Gain .............................................................................................................................. 23 Read Offset ............................................................................................................................ 23

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Loadcell Loadcell FBs, located on the FB menu, enable you to include an I/O module that is connected to a loadcell or strain-gauge in your control application. Unitronics I/O expansion loadcell modules are intelligent I/O modules that are capable of receiving analog values directly from loadcells.

IO-LC1 offers 1 Loadcell input; IO-LC3 module offers 3 Loadcell inputs. Each IO-LCx module is capable of providing excitation for up to 12 loadcells.

The Loadcell FBs enable you to calibrate the loadcell. You can also tare and zero the loadcell, compensate for deadload and scale movement, and set the input range.

Once you connect the loadcell and calibrate at least 2 points, you can begin to run a loadcell application. The loadcell input can be read in 6 different ways:

Gross weight Net weight Net Min. Weight Net Max. Weight Scaled to uV/V Raw Value

Most applications will require only the Gross or Net weight. Raw Value and uV/V readings may be useful for troubleshooting purposes.

Loadcell Quickstart FB Operations C o n f i g u r a t i o n

S c a n

C a l i b r a t i o n

S e t u p

T a r e & Z e r o

A d v a n c e d

Note ♦ Both negative and positive (signed and unsigned) values can be processed by

the I/O-LCx and the support software, enabling a range of applications.

Loadcell applications are included when you install VisiLogic. These sample applications may be found by clicking Help on the VisiLogic toolbar, and then selecting Examples.

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Loadcell Help Rev: 17/06/04 Loadcell FBs, located on the FB menu, enable you to include an I/O module that is connected to a loadcell or strain-gauge in your control application. Unitronics I/O expansion loadcell modules are intelligent I/O modules that are capable of receiving analog values directly from loadcells.

IO-LC1 offers 1 Loadcell input; IO-LC3 module offers 3 Loadcell inputs. Each IO-LCx module is capable of providing excitation for up to 12 loadcells.

The Loadcell FBs enable you to calibrate the loadcell. You can also tare and zero the loadcell, compensate for deadload and scale movement, and set the input range.

Once you connect the loadcell and calibrate at least 2 points, you can begin to run a loadcell application. The loadcell input can be read in 6 different ways:

Gross weight Net weight Net Min. Weight Net Max. Weight Scaled to uV/V Raw Value

Most applications will require only the Gross or Net weight. Raw Value and uV/V readings may be useful for troubleshooting purposes.

Loadcell Quickstart FB Operations C o n f i g u r a t i o n

S c a n

C a l i b r a t i o n

S e t u p

T a r e & Z e r o

A d v a n c e d

Note ♦ Both negative and positive (signed and unsigned) values can be processed by

the I/O-LCx and the support software, enabling a range of applications.

Loadcell applications are included when you install VisiLogic. These sample applications may be found by clicking Help on the VisiLogic toolbar, and then selecting Examples.

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Loadcell Hardware Configuration The IO-LCx Hardware Configuration enables you to configure a loadcell, plus the digital input and digital outputs located on the module. These digital I/Os enable you to implement setpoints that are processed within the I/O module, independently of the controller and its program scan, enabling a fast response to process events.

Configuring a Loadcell The number of Loadcell tabs in the Hardware Configuration window depends upon the loadcell module.

Parameter Type Function

I n use Se lec t ' I n Use ' to enab le the loadce l l f o r the app l i ca t ion . Note ♦ A l oadce l l marked ' i n use ' can be suspended accord ing to app l i ca t i on cond i t i ons v ia the Advanced Ca l ib ra t i on func t i on Enab le /D isab le l oadce l l . Th is may be done to shor ten the app l i ca t i on 's ca l i b ra t i on t ime .

Reso lu t i on ML, MI

Se lec t i ng H igh enab les you to l i nk the inpu t va lue to an ML, Norma l to an MI .

LC Input Va lue (s ) MI , ML

When the app l i ca t i on runs , these reg is te rs con ta in the we igh t va lue inpu t to the cont ro l l e r f rom the I /O LCx . When you se lec t two va lues , you l i nk the f i rs t va lue to a s ing le reg is te r . The second va lue i s automat ica l l y l inked to the nex t reg is te r . The de fau l t rep resen ta t i on mode fo r the f i rs t reg i s te r i s Net Weight , and Gross Weight f o r the second reg i s te r .

Exc i ta t i on AC i s the de fau l t , recommended Exc i ta t i on method . You may se lec t the DC op t ion i f you r app l i ca t ion requ i res .

Hardware S ta tus Messages

MI P rov ides a b i tmap showing the s ta tus o f the modu le .

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Loadcell: Configuration All Loadcell operations run through a Loadcell Configuration placed in the control program. Each Configuration is linked to a specific Loadcell input on the I/O expansion module.

Loadcell Configuration is generally a Power-up task. The Loadcell Configuration FB is located on the FB's>Loadcell menu.


I/O Module DIN Location

L inks the Con f igu ra t ion w i th the co r rec t I /O expans ion modu le acco rd ing to i t s D IN ra i l l oca t i on in Hardware Con f igu ra t i on .

On th i s DIN ra i l , t he I /O LC3 i s modu le # 2

Note ♦ I f t he modu le i s no t l oca ted in the en te red loca t i on , the LC Command S ta tus Messages MI w i l l d i sp lay 6 , Commun ica t i on Er ro r ( I /O modu le does no t ex i s t )

Loadcell Input Number

Here , Loadce l l 2 i s be ing shown as marked ' I n Use ' .

Note ♦ I f t he se lec ted Loadce l l i s no t marked ' I n Use ' , t he LC Command S ta tus Messages MI w i l l d i sp lay 11 , I l l ega l pa ramete r

LC Command Status Messages

MI • I s rese t to 0 when a command i s ac t i va ted . • Updated a t the end o f a l l opera t ions us ing the Loadce l l

Con f igu ra t ion . • I nd ica tes e r ro r s ta tus fo r a l l l oadce l l ope ra t ions p rocessed by the

Con f igu ra t ion • Cur ren t va lue a lways shows the mos t recent e r ro r s ta tus .

Value Message

0 Func t i on in Prog ress

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1 Command ca r r i ed ou t success fu l l y

2 I /O Expans ion Command Bu f fe r i s fu l l , p lease re t r y . Can be avo ided by us ing SB 91 , I /O Expansion Module - -Command Buf fer Fu l l , as a cond i t i on

3 The I /O expans ion modu le l i nked to the conf igu ra t ion i s busy

5 T imeout Exceeded

6 Communica t ion Er ro r ( I /O modu le does no t ex i s t )

11 I l l ega l pa ramete r

13 Power supp ly no t connec ted

16 Sca le i s cu r ren t l y i n mo t ion ( i s on ly re levant i f In -Mot ion func t ion i s app l ied )

17 S igna l i s ou t o f range ( th is va lue occurs when the Out o f Range b i t i s ON)

18 I l l ega l we igh t (Occurs du r ing ca l i b ra t i on , i f the raw va lue o f we igh t be ing ca l i b ra ted i s too c lose to the raw va lue o f an a l ready ca l i b ra ted we igh t ; m in imum d is tance i s 256 o r 100 Hex)

19 Command no t suppor ted in uV /V mode

20 No t ca l i b ra ted (Th is va lue appears when less than 2 po in ts have been ca l i b ra ted )

21 EEPROM Pro tec t i on Er ro r ( Ind ica tes when too many Save Ca l ib ra t i on FBs a re run too f requen t l y . Check the ac t i va t i ng cond i t i ons fo r the Save Ca l ib ra t i on FB, and whe ther your app l i ca t i on con ta ins loops )

LC Success Bit MB Use th i s to mon i to r the s ta tus o f a command

Turns ON w hen: • Conf igu ra t ion i s f i rs t

ac t i va ted . • Command is success fu l l y

p rocessed . • Command S ta tus Messages

MI i s 1 .

Turns OFF when: • Command S ta tus Messages

MI i s 0 . • Func t i on in Prog ress MB i s

ON, i nd ica t i ng tha t a command i s be ing p rocessed .

• Command e r ro r occurs Function in Progress

MB Th is b i t i s ON when the modu le i s p rocess ing a command. Use th i s as a cond i t i on b i t f o r Loadce l l opera t ions to avo id con f l i c ts .

Turns ON when: • Command i s be ing

p rocessed . • Command S ta tus Messages

MI i s 0 .

Turns OFF when: • Conf igu ra t ion i s f i rs t

ac t i va ted . • Command S ta tus Messages

MI i s 1 .

LC

SuccessFunction in

LC Command Status

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Bit Progress Messages Command

Issued 0 1 0

Success 1 0 1 Error 0 0 >1

Scan A Scan FB must be included for every Loadcell Configuration in a Loadcell application. When an application contains more than 1 Loadcell Configuration in the Ladder, the Scan FB displays the Select Name drop-down list, enabling you to link the desired Configuration.

The Scan FB is located on the FB>Loadcell menu.

Note

♦ The Scan FB must be on the left-hand ladder rail.

Calibration Calibration parameters include calibrated points, input range settings, tare and zero values. These may be burned to the module's EEPROM using the Save Calibration FB. Before you can begin to implement a Loadcell application, you must calibrate at least two points, although up to 12 points may be calibrated; all other calibration parameters are optional. However, note that if the application requires you to set Input Range/Gain, you must make these settings before you calibrate points. Setting the Input Range/Gain after calibrating points invalidates these points.

Calibrating Points A Calibration Point matches a Raw Value with a Weight value. These points are used to linearize the input value.

To calibrate points, connect the controller to the loadcell via the I/O-LCx. Initial calibration is generally performed with known weights as shown in the following figure. After calibration has been performed, advanced calibration enables points to be added or edited via the ladder without weight being physically placed on the loadcell.

Loadcell

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Notes ♦ If the application requires you to set Input Range/Gain, you must make these settings before you calibrate points. Setting the Input Range/Gain after calibrating points invalidates the calibrated points.

♦ Zero does not have to be calibrated. ♦ Points do not have to be calibrated in any particular order. ♦ All calibrated points must be separated by a raw value minimum of 25 (100 Hex). ♦ Calibration is an immediate operation; motion is not checked before the operation

is carried out. ♦ Calibration should be performed with greater accuracy than is required by the

application. For example, in an application that requires 100g accuracy, calibrate in units of 10g, then round off the represented value by 10.

♦ The highest Calibrated Point weight value should 80–100% of the scale capacity. ♦ Calibration cannot not be performed if the selected representation mode is uV/V. ♦ During calibration, increase filter depth by:

- Increasing Settling Time. - Disabling other Loadcells.

Calibrate Point FB The Calibrate Point FB is located on the FB's>Loadcell>Calibration menu.

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Point Number Cons tan t , M I

A Ca l ib ra t i on Po in t ma tches a we igh t va lue w i th a raw va lue . The raw va lue i s acqu i red as an inpu t f rom the loadce l l when the app l i ca t ion i s run .

Calibrate to Weight

MI , ML Th is p rov ides the we igh t va lue tha t i s ma tched to the raw va lue

Save Calibration When you save the calibration, calibrated points, tare, zero, and input range are burned into the module's EEPROM memory. This protects the calibration in the event of a power outage, reset, or power-up. To preserve any changes made to calibrated points, input range settings, tare and zero values, use Save Calibration any time these parameters are edited.

Tare & Zero Applying Tare and Zero accomplish the same aim: to start a weighing session with a value of zero.

The Tare value may include, for example, the container of the material to be weighed.

If the scale does not read 0 when empty, use Zero to compensate.

When Tare is applied, it is reflected in the net weight.

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When Zero is applied, both the net and gross weights will be zero at the beginning of a weighing session.

Tare & Zero Acquire Tare/Zero FB: value read from Loadcell

Acquire Tare and Acquire Zero are both located on the FB's>Loadcell>Tare & Zero menu.

Acquire Tare: In this method, the tare value is acquired from the scale. The objects comprising the tare, such as a pallet or materials container, are placed on the scale, and Acquire Tare is activated.

Acquire Zero: The scale must be empty to acquire Zero. Acquire Zero is not related to the Auto-Zero Tracking function, which enables the module to compensate for the accumulation of undesired material on the scale in the course of operations.

Note ♦

Loadcell Name determines from which loadcell the tare/zero will be acquired. After the tare has been acquired, the tare value will be applied to that loadcell.

♦ Use the Save Calibration FB to save Tare and Zero values to the module's EEPROM memory.

♦ Tare and Zero cannot be acquired when running uV/V mode. ♦ If the Motion Band FB is activated, the tare value cannot be acquired until the scale

is stable.

Although only the FBs relating to tare are pictured in the following figures, the figure apply to both Tare and Zero FBs.

Advanced Tare& Zero Functions

These FBs are both located on the FB's>Loadcell> Advanced> Tare & Zero menu.

Edit Tare/Zero: value via operand or constant


Tare/Zero Value

MI , ML , o r Cons tan t

Ed i t Ta re /Zero enab les the ta re va lue to be acqu i red f rom a reg is te r o r cons tan t va lue w i th in the con t ro l l e r . You can a l so use Ed i t Ta re /Zero to change a loadce l l ' s ex i s t i ng ta re /ze ro va lue .

Loadcell

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Read Tare/Zero: reading the current Tare or Zero Value


Read Tare/Zero MI , ML

Reads the cur ren t ta re o r ze ro va lue app l ied to the l i nked loadce l l i npu t i n to the l i nked reg is te r .

Setup Setup FBs provide additional parameters that you may require for your application. Setup FBs include Motion Band, Filter & Rounding, and Auto-Zero, and are located on the FB's>Loadcell>Setup menu.

Motion Band When the weight on the scale changes, the scale needs time to stabilize. The Motion band determines the amount of weight change the module uses to decide if the scale is in motion. Bit 0, of the MI that is linked to LC Hardware Status Messages in Hardware Configuration, is the In-motion indicator. Bit 0 is ON when the scale is in motion, and OFF when the scale is steady. As the module reads the signals from the loadcell(s) it calculates the weight value. If a weight change falls within the Motion Band, Bit 0 turns ON. In the accompanying figure, the in-motion indicator (Bit 0) turns ON when the weight change is below 100 grams, or more than 500 grams. When the weight change falls within the band, Bit 0 turns OFF.

Notes ♦ The FB must be activated in order to apply the Motion Band. ♦ The In-motion indication is OFF when:

- at Power-up - or The scale is not calibrated.

♦ In order for the In-Motion indication to function properly, the filter Active Band

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must be equal or higher than the In-Motion Tolerance. Refer to the Filter and Rounding function for description and power-up defaults.

♦ If the Motion Band is active, the tare/zero values cannot be acquired when the scale is in motion.


LC Motion Band


P rov ides a va lue fo r the we igh t band . A we igh t change tha t fa l l s ou ts ide th i s band tu rns the In -mot ion b i t ON. When the we igh t change i s i ns ide the band , the b i t t u rns OFF.

Filter and Rounding The Filter & Rounding parameters change the default filter parameters and value rounding. Rounding further smooths the loadcell reading.


Rounding MI o r Cons tan t

The number used to round the ou tpu t va lues . 0 - Round by 1 (Power -up de fau l t ) 1 - Round by 2 2 - Round by 5 3 - Round by 10 4 - Round by 20 5 - Round by 50 6 - Round by 100 Note ♦ Va lue round ing w i l l no t take e f fec t i n uV/V and Raw va lue rep resenta t i on modes .

Settling Time MI ,o r Cons tan t

The t ime , i n un i ts o f 10msec , tha t the f i l t e r requ i res to se t t l e to the f i na l read ing . Notes ♦ The de fau l t se t t l i ng t ime i s 1 second , the m in imum t ime 1 i s 12 .5 m i l l i seconds , and the max imum i s 24 seconds . ♦ A va lue o f ze ro d i sab les the f i l t e r . ♦ Set t l i ng t ime r i ses w i th the number o f ac t i ve loadce l l s . The min imum se t t l i ng t imes a re : - 12 .5ms for one ac t i ve loadce l l . - 675ms for two ac t i ve loadce l l s . - 1 ,012 .5ms fo r th ree ac t i ve loadce l l s . Us ing a se t t l i ng t ime o f ze ro se ts the se t t l i ng t ime to i t s m in imum va lue w i thout re tu rn ing an e r ror .

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Active Band MI , ML , o r Cons tan t

The band o f we igh t changes in wh ich the f i l t e r i s ac t i ve . The f i l t e r i s tu rned o f f by we igh t changes tha t exceed the ac t i ve band . Th is a l l ows a rap id response to l a rge we igh t changes . When the we igh t changes become sma l le r than the ac t i ve band , the f i l te r tu rns on . An ac t i ve band o f ze ro fo rces the f i l t e r to be a lways ac t i ve . Notes ♦ I f t he Mot ion Band i s on , the f i l t e r ' s Ac t i ve Band mus t be equa l o r h igher than the Mot ion Band .

Auto Zero Tracking

When activated, Auto-Zero Tracking zeros the gross weight according to the conditions you set, enabling the module to automatically compensate for small variations at the zero point, such as those caused by a buildup of litter on the scale platform, or by temperature fluctuations near the scale.

Before Auto-zero Tracking can zero the scale:

The Motion Band FB must be included in the application. The Motion Band must be active. The In-Motion bit, Bit 0 of the MI linked to LC Hardware Status Messages in Hardware

Configuration, must already have turned OFF, indicating that the scale is steady. Once these condition have been met, Auto-zero zeros the gross weight.

Notes ♦ Once Auto-Zero tracking is activated, it stays active until the function is suspended by the application.

♦ Auto zero tracking will not function in uV/V representation mode.


LC Time: Scale Stable, 10 mS units

MI , ML o r Cons tan t

The t ime in wh ich , i n un i ts o f 10 mSec , the sca le mus t be s tab le i n o rde r to t r i gge r Au to -Zero T rack ing . Notes ♦ I n i t i a l i z ing th i s pa ramete r to 0 w i l l t u rn o f f Au to Zero T rack ing and c lea r the accumula ted o f fse t . ♦ Power -up de fau l t : 0 (au to ze ro t rack ing i s o f f ) . ♦ To c lea r the au to ze ro t rack ing o f f se t , i n i t i a l i ze th i s pa ramete r to 0 , and then en te r a new t ime va lue .

LC Tracking band, Weight from last Auto-0


Th is de te rmines the max imum d is tance f rom the po in t o f the las t ze ro (au to o r manua l ) i n wh ich au to-ze ro t rack ing i s ac t i va ted [we igh t un i ts ] .

LC Tracking Range, Weight from Calib. 0


Th is de te rmines the max imum we igh t f rom the po in t o f the las t ca l i b ra ted zero i n wh ich au to -ze ro i s ac t i va ted .

Loadcell Operands & Status Messages

Loadcell

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Loadcell: Configuration FB All Loadcell operations run through a Loadcell configuration placed in the control program. Each Configuration is linked to a specific Loadcell input on the I/O expansion module.

Command Status Messages I n i t i a l i zed to 0 when Loadce l l Conf igura t ion i s ac t i va ted .

MI • I s rese t to 0 when a command i s ac t i va ted . • Updated a t the end o f a l l opera t ions us ing the Loadce l l

Con f igu ra t ion . • I nd ica tes e r ro r s ta tus fo r a l l l oadce l l opera t ions

p rocessed by the Con f igu ra t ion • Cur ren t va lue a lways shows the mos t recent e r ro r s ta tus .

Value Message

0 Func t i on in Prog ress

1 Command ca r r i ed ou t success fu l l y

2 I /O Expans ion Command Bu f fe r i s fu l l , p lease re t ry . Can be avo ided by us ing SB 91 , I /O Expansion Module - -Command Buf fer Fu l l , as a cond i t i on

3 The I /O expans ion modu le l i nked to the con f igu ra t i on i s busy

5 T imeout Exceeded

6 Communica t ion Er ro r ( I /O modu le does no t ex i s t )

11 I l l ega l pa ramete r

13 Power supp ly no t connec ted

16 Sca le i s cu r ren t l y i n mo t ion ( i s on l y re levant i f I n -Mot ion func t i on i s app l ied )

17 S igna l i s ou t o f range ( th is va lue occurs when the Ou t o f Range b i t i s ON)

18 I l l ega l we igh t (Occurs du r ing ca l i b ra t i on , i f the raw va lue o f we igh t be ing ca l i b ra ted i s too c lose to the raw va lue o f an a l ready ca l i b ra ted we igh t ; m in imum d i s tance i s 256 or 100 Hex)

19 Command no t suppor ted in uV /V mode

20 No t ca l i b ra ted (Th is va lue appears when less than 2 po in ts have been ca l i b ra ted )

21 EEPROM Pro tec t i on Er ro r ( Ind ica tes when too many Save Ca l ib ra t i on FBs a re run too f requen t l y . Check the ac t i va t i ng cond i t i ons fo r the Save Ca l ib ra t i on FB, and whe ther your app l i ca t ion con ta ins loops )

LC Success Bit MB Turns ON when:

• Conf igu ra t ion i s f i rs t ac t i va ted .

• Command i s success fu l l y

Turns OFF when: • Command S ta tus Messages MI

i s 0 . • Func t i on in Progress MB i s ON,

i nd i ca t i ng tha t a command i s

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processed . • Command S ta tus

Messages MI i s 1 .

be ing p rocessed .

Function in Progress

MB Turns ON when: • Command i s be ing

p rocessed . • Command S ta tus

Messages MI i s 0 .

Turns OFF when: • Conf igu ra t ion i s f i rs t ac t i va ted . • Command S ta tus Messages MI

i s 1 .

Loadcell Hardware Status Messages (Hardware Configuration) The MI l i nked to the pa ramete r LC Hardw are Sta tus Messages i n Hardware Con f igu ra t ion p rov ides a b i tmap fo r the fo l l ow ing messages .

Bit# Description Turns ON when: Turns OFF when:

0 Sca le mo t ion On ly re levan t i f Mo t ion Band FB i s i nc luded in app l i ca t i on and ac t i va ted

Sca le i s i n mo t ion • At Power -up • When Sca le i s

s teady

1 Inpu t Va lue Range L inked to I /O modu le 's Out o f Range LED ind ica to r

Inpu t va lue i s ou t o f range Poss ib le causes : • 1 o r more s igna l w i res

a re d i sconnec ted • A/D input vo l tage i s ou t

o f range

Inpu t va lue i s i n range

2 Inpu t Va lue Va l id i t y

I npu t Va lue i s i nva l i d Poss ib le causes : • Channe l i s tempora r i l y

d i sab led , v ia the D isab le a l l o the r Loadce l l s FB

• Bi t i s ON a t Power -up un t i l t he f i rs t i npu t va lue i s rece ived f rom the loadce l l

I npu t Va lue i s va l i d

3 Loadce l l Ca l ib ra t ion S ta tus When less than 2 po in ts a re ca l i b ra ted

A t l eas t 2 po in ts a re ca l i b ra ted

No Power Power Supp ly OK 4 Inpu t Power Supp ly S ta tus L inked to I /O modu le 's Out o f Range LED ind ica to rs • When the inpu t power i s no t supp l ied , the

i nd i ca to rs b l inks rap id l y

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Note ♦ Bi ts 6 & 7 a re l i nked to Outpu ts 0 & 1 , l oca ted on the I /O modu le . B i t 6 i s re la ted to Outpu t 0 , B i t 7 to Ou tpu t 1 . B i ts 6 & 7 can be used to mon i to r the se tpo in t ou tpu t ' s s ta tus f rom wi th in the Ladder app l i ca t ion . The I /O modu le i t se l f con t ro l s the se tpo in t func t i on o f the ou tpu ts . The modu le tu rns the ou tpu ts ON and OFF when the cu r ren t l oadce l l i npu t va lue reaches se tpo in t . S ince the func t ion i s based in the f i rmware o f the expans ion modu le , when the ou tpu t 's s ta tus changes as a resu l t o f reach ing /depar t ing f rom se tpo in t , t he s ta tus change i s no t reg is te red by the Ladder app l i ca t ion . Examp les • When se tpo in t ou tpu t 1 i s ass igned to l oad ce l l channe l 0 , B i t 7 o f l oad ce l l 0 s ta tus

w i l l i nd ica te the s ta te o f ou tpu t 1 . • When se tpo in t ou tpu t 0 i s ass igned to l oad ce l l channe l 2 , B i t 6 o f l oad ce l l 2 s ta tus

w i l l i nd ica te the s ta te o f ou tpu t 0 .

6 Se tpo in t S ta tus , Outpu t 0 Ou tpu t 0 i s ON Outpu t 0 i s OFF

7 Se tpo in t S ta tus , Outpu t 1 Ou tpu t 1 i s ON Outpu t 1 OFF

SB91 I /O Exp . Modu le - -Command bu f fe r i s fu l l

ON when an I /O i s p rocess ing a command.

OFF when an I /O i s i d le .

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Advanced Loadcell Functions

Advanced Functions

Advanced Functions

Advanced-Calibration These FBs are all located on the FB's>Loadcell> Advanced> Calibration menu.

Note ♦

The Edit and Read Calibration Point functions contain parameters which accept the raw and weight values from existing Calibration Points. These parameters must be linked to the same type of registers, MI or ML, used to calibrate the original Calibration Point.

Edit Calibration Point: value via operand or constant A Calibration Point matches a raw value to a weight value. You can use Edit Calibration Point to change these values.

Notes ♦

The loadcell will stop functioning if deleting a point causes the number of Calibration Points to be less than 2.

♦ To prevent your changes from being lost at power-up, reset, or in the event of power outage, use the Save Calibration FB to burn the changes to the module's EEPROM.

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LC Calibration Point Number

MI o r Cons tan t

The number o f the Ca l ib ra t i on Po in t tha t you w ish to ed i t .

LC Raw Value

MI , o r ML

Th is reg i s te r con ta ins the new raw va lue fo r the Ca l ib ra t ion Po in t .

LC Calibrate to Weight

MI , o r ML

Th is reg i s te r con ta ins the new we igh t va lue fo r the Ca l ib ra t ion Po in t .

Read Calibration Point Use this function to read the current raw and weight values of a Calibration Point.

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Note ♦

If the point being read is not in use, both returned values will be -32768 (0x8000) for integer and -8388608 (0x800000) for long.



MI o r Cons tan t

The number o f the Ca l ib ra t i on Po in t tha t you w ish to read .

LC Raw Value

MI , o r ML

Th is reg i s te r con ta ins the cu r ren t raw va lue o f the Ca l ib ra t ion Po in t t .

LC Calibrate to Weight

MI , o r ML

Th is reg i s te r con ta ins the cu r ren t we igh t va lue o f the Ca l ib ra t i on Po in t .

Delete Calibration Point This deletes a Calibration Point.

Notes ♦

The loadcell will stop functioning if a deleted point causes the number of Calibration Points to be less than 2.

♦ To prevent your changes from being lost at power-up, reset, or in the event of power outage, use the Save Calibration FB to burn the changes to the module's EEPROM.



MI o r Cons tan t

The number o f the ca l i b ra ted po in t tha t you w ish to de le te .

Clear Calibration This deletes all calibrated points, tare, zero, and input ranges from the module's memory. However, Clear Calibration does not erase the values from the EEPROM. They may be retrieved from the EEPROM by resetting the controller.

To delete all values from the EEPROM, run Clear Calibration followed by Save Calibration.


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Enable/Disable all other load cells

Disable All Other Loadcells disables all loadcells configured in the application except for the loadcell selected in the FB.

During Calibration, the Disable All Other Loadcells FB can be used to increase filter depth for a specified settling time by eliminating the delay caused by channel change (approx. 300ms) and thus ensuring faster and more accurate calibration.

To prevent channel changing from wasting settling time, use this function to disable all other loadcells except for the one you are currently calibrating.

Enable All Other Loadcells re-enables all loadcells configured in the application.

Notes ♦

After this FB is run, and the Command Status Messages MI linked to the selected Loadcell Configuration indicates 1, updated values for all of the enabled channels are already available at their linked operands. This indication can be used to trigger a process, such as calibration.

♦ Disabled Loadcells: the Command Status Messages MI linked to the selected Loadcell Configuration The status bit "Value not valid" will rise in the disabled load cells' status word.

Setpoint Each digital output located on the I/O module is associated with a setpoint. The I/O module itself controls the setpoint function of the outputs. The module turns the outputs ON and OFF when the current loadcell input value reaches setpoint. Setpoint activity is therefore not linked to the program scan. Each output may be assigned a setpoint.

Since the function is based in the firmware of the expansion module, when the output's status changes as a result of reaching/departing from setpoint, the status change is not registered by the Ladder application. To monitor the outputs' status, this MI provides a bitmap indicating status messages; Bit 6 is related to Output 0, Bit 7 to Output 1.

Therefore, use Bits 6 & 7 of the LC Hardware Status Messages MI to monitor the outputs' status, from within the Ladder application.

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Note ♦

Once the Setpoint is activated, it cannot be changed by setting the output via the Ladder application.

The setpoint remains OFF, regardless of its N.O./N.C.setting, when the loadcell input value is: - invalid (i.e., powered off, LC disabled, out of range, loadcell not calibrated. - In uV/V mode.

Examples

When setpoint output 1 is assigned to load cell channel 0, Bit 7 of load cell 0 status will indicate the state of output 1.

When setpoint output 0 is assigned to load cell channel 2, Bit 6 of load cell 2 status will indicate the state of output 0.

Bi t Descr ip t ion Turns ON w hen: Turns OFF w hen:

6 Se tpo in t S ta tus , Outpu t 0 Ou tpu t 0 i s ON Outpu t 0 i s OFF

7 Se tpo in t S ta tus , Outpu t 1 Ou tpu t 1 i s ON Outpu t 1 OFF

Set and Activate Setpoint Use this FB to implement a desired setpoint.


LC Value Mode

Cons tan t Se t the inpu t va lue mode fo r the se tpo in t : • 0 - Net • 1 - Gross • 2 - Net M in • 3 - Net Max

LC Output Number

Cons tan t Se lec t ou tpu t : • Ou tpu t - 0


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• Ou tpu t - 1

LC Setpoint Type


Se lec t se tpo in t t ype : 0 - Norma l s ta te : Open Ac t i va t i on : Low 1 - Norma l s ta te : Open Ac t i va t i on : H igh 2 - Norma l s ta te : C losed Ac t i va t i on : Low 3 - Norma l s ta te : C losed Ac t i va t i on : H igh

LC Setpoint Value


The ac tua l va lue ass igned to the se tpo in t .

LC Setpoint Hysteresis


Se ts a band in wh ich the ou tpu t w i l l no t cha t te r due to ove rshoo t o r v ib ra t ions .

Deactivate Setpoint Use this to suspend the activity of a particular setpoint.

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Change Representation Mode During hardware configuration, under Number of values, you select whether to use one or two values. When you select a register for the Address: Value(s) parameter, selecting two values means that the register immediately following the register you select is used for the second value. The default representation mode for the first register is Net Weight, and Gross Weight for the second register.

Via Change Representation mode, you can 'read' the value as:

Gross weight Net weight Net Min. Weight Net Max. Weight Scaled to mV Raw Value

Reset Net Min/Max Values Resets the Net Minimum value to positive full-scale, and the Net Maximum value to negative full-scale.

As soon as the scale becomes stable, meaning that the In-motion bit is OFF, the Net Min and Max values will be set to the net value.

A Net Min and Max reset occurs also at power-up.

Change Excitation Mode Use this FB to temporarily change the excitation supplied to the loadcell.

Input Range The Input Gain parameter sets the amplification range for the input signal.

The Offset parameter is generally used to compensate for the deadload; particularly in cases where the combined weight of deadload and payload exceed the A to D converter input range.

Input Range and Offset are considered part of the loadcell's calibration. To burn these values into the module's EEPROM memory and protect them in the event of a power outage, use the Save Calibration FB.

Set Gain FB This FB limits the input range. The gain is applied to the signal after offset compensation.

Setting the Set Gain MB to 0 limits the input range to ±20mV (Default setting), setting it to 1 (or any other value) limits the input range to ±80mV.


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Set Offset This FB sets the offset compensation, which is applied to the input signal before the gain. By default, the offset is set to 0mV (no offset).

Possible values are in the range of ±31, where: 1LSB ≈ 0.5mV/V (= 2.5mV at exactly 5V excitation). Hence, the maximum offset compensation is ±15.5mV/V (= ±77.5mV at exactly 5V excitation).

To calculate the offset value, measure the differential voltage at the input, between the -SG and +SG terminals, and then calculate the offset value according to 1LSB ≈ 0.5mV/V.

If, for example, the differential voltage at the input is 10mV, use -4 as the offset value.

Read Gain Reads the input range Gain.

Read Offset Reads the input range Offset.

Notes ♦

Changing Gain or Offset requires you to recalibrate and save all calibrated points.

♦ If the application requires you to set Input Range/Gain, you must make these

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settings before you calibrate points. Setting the Input Range/Gain after calibrating points invalidates the calibrated points.

♦ Offset values out of the ±31 range will be truncated and no error will be returned. ♦ The uV/V rep. mode uses its own input range settings and therefore is not affected

by the command.

Documents

Loadcell - Serwer pomocy technicznej Elmark …support.elmark.com.pl/unitronics/PDF/Loadcell.pdf · Loadcell: Configuration ... Loadcell: Configuration All Loadcell operations run