i4SCADA Knowledge Base

Edit Signals in the Signal Details panel

Abstract

Signals are the basic components of your i4SCADA Studio Project. Learn everything you need to know about the i4SCADA Signals.

Once the signals are imported or defined in the i4SCADA Studio, they can be configured using the Signal Details panel. This panel is available at the bottom of the signals view and it is collapsed by default.

The Signal Details panel displays the complete set of signal properties. The same properties are available in the signals view. The Signals Details panel is split in two tabs: General, containing the general signal properties and VChannel, containing the virtual channels and scripts-related signal properties.

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Signal Details Panel

Any change applied in the Signal Details panel is applied only when the Save button is pressed.

General tab

The General tab contains the general signal properties. These properties can be found also in the signals grid.

UI Option

Description

Active

If checked, the signal is active in i4SCADA Server.

Signal name

The name of the signal in i4SCADA Studio.

Description 

Optional signal description.

Connector address

The address of the signal in the OPC Server.

Write group

The write group to which the signal belongs.

Discrete Value Type

The combining group of discrete values. The discrete values are used by WEBfactory Scheduler to manipulate a device depending on the hour of the day.

The Discrete Value Type containing several discrete values can be attached to a process signal (in the Signal list) so that WEBfactory Scheduler can assign the value of one of the Discrete Values inside the Discrete Value Type to the process signal when needed.

OPC enables

Works in conjunction with the WEBfactory Server acting as an OPC server (usually the WEBfactory Server acts as an OPC client).

When this option is enabled, the signal value will be sent to the WEBfactory WCS OPC server, so other OPC clients can access the value from the WEBfactory Server like from an OPC server.

Log User Activity

If checked, the user activity for this signal will be logged. This setting is key to the i4SCADA HTML User Manager (function User Actions - User writes signal events).  

Factor X1

A real value of the PLC used to transform the signal value using a mathematical formula into a SCADA readable value Y1. The transformation is based on a XOY coordinate system and needs 4 values (X1, X2, Y1, Y1) to be applied.

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SCADA Values example

Factor X2

A real value of the PLC used to transform the signal value using a mathematical formula into a SCADA readable value Y2. The transformation is based on a XOY coordinate system and needs 4 values (X1, X2, Y1, Y1) to be applied.

Factor Y1

The SCADA value of the X1 PLC value. The transformation is based on a XOY coordinate system and needs 4 values (X1, X2, Y1, Y1) to be applied.

Factor Y2

The SCADA value of the X2 PLC value. The transformation is based on a XOY coordinate system and needs 4 values (X1, X2, Y1, Y1) to be applied.

Minimum

Sets the minimum signal value for writing. If a value smaller than this limit is written, the minimum value will be sent to the control unit.

Maximum

Sets the maximum signal value for writing. If a value bigger than this limit is written, the maximum value will be sent to the control unit.

Unit

Optional measurement unit for the signal's value. If present, the unit can be used further in visualizations.

Substitute value

Enables the usage of the substitute values. If checked, a substitute value is used when the minimum value is not reached or the maximum value is exceeded.

Hysteresis

Sets absolute or relative hysteresis value for signal visualization.

Hysteresis refers to the difference between consecutive signal values. It can be used to filter field-level signals, so that the output reacts less rapidly than it otherwise would, by taking recent system history into account.

In other words, hysteresis is the difference between continuously rising and falling values, usually desirable in applications where multiple signal values fluctuations may occur.

Tip

For example, a thermostat controlling a heater may switch the heater on, when the temperature drops below 18 °C, but not turn it off until the temperature rises above 20 °C.

Log Hysteresis

Sets absolute or relative hysteresis value for logs.

The scope of Log Hysteresis is to properly log signal values that may include small variations over time. When a Logging hysteresis value is set, only those values that have changed more than the set value will be stored. If the change is less than the Logging hysteresis value, the log point will not be stored. The advantage of hysteresis logging is that the log interval can be shorter than for standard logging, (e.g. every 10 seconds), but at the same time, the logged data to be stored can be limited to just the data that is of the greatest interest. Logging hysteresis is not designed to store every single log sample, but is instead intended to allow the logging of greater changes that appear within a limited time.

Alarm Hysteresis

Sets absolute or relative hysteresis value for alarms.

Alarm hysteresis works with the high and low alarm thresholds to tel the connector when to keep an alarm on, without sending additional alarm reports, or when to shut it off. The Alarm hysteresis is used to avoid repeated alarms during signal values fluctuations.

Tip

Hence, in a Vibration Monitoring System, a Vibration signal can record values that overcome the high alarm threshold causing the connector to send a high alarm report. Note that during this alarm condition, the value of the Vibration signal may continue to increase and decrease repeatedly between normal and high thresholds. In this situation, without a defined hysteresis range, the Vibration Monitoring System connector sends an alarm report every time the Signal value is at its high threshold.

Alarm State

Description

On

The connector measures that the vibration has overcome the high threshold. An alarm is triggered.

On

The connector measures that the vibration has decreased below the high threshold, but it is still above the hysteresis so the alarm remains on. If the signal value increases again above the high threshold, no additional alarm is triggered.

Off

The vibration decreases below the hysteresis so the alarm is turned off. If the signal value increases again above the high threshold, the alarm turns on and the connector triggers another alarm.

Assigned to log(s)...

Notifies the user if the selected signal is assigned to any logs. Clicking on the link will open the logging panel.

Assigned to alarm(s)...

Notifies the user if the selected signal is assigned to any alarms. Clicking on the link will open the alarming panel.

VChannel tab

The VChannel tab allows the user to generate virtual signals in WEBfactory Studio. The virtual signals can be used to create scripts for various tasks using different signal values or to generate collective alarms.

Learn more about i4SCADA Virtual Channels and Scripting here.

The virtual signals are created using VChannels (virtual channel). The VChannel's input parameters are the signal values. Several VChannels can be linked one to another.

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VChannel TAB

The VChannel can be activated or deactivated using the Activate VChannel checkbox. The Calculation base of the VChannel can be either Script or Collective Alarm.

Script

The Script calculation base allows the user to define a VB script in the script editor using signal variables as input signals.

UI Option

Description

Initialization value

Sets a constant (named MyInitValue). When the system starts, the MyInitValue constant will be made available.

Data type

Set the data type for the WriteSignal () function. Can be:

  • Default: Float, Integer or Boolean

  • String

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Input signal's index number. Input signals are referenced in the script by index numbers.

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Move the input signal up in the list. The signal's index number changes.

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Move the input signal down in the list. The signal's index number changes.

Add

Opens the Select Parameter window that allows the user to add signal as input signals.

Remove

Remove the selected input signal.

Signal Value

Sets the starting signal value for the MySignalValue variable.

The MySignalValue variable is used to query the value of the virtual signal variable.

Result

The script’s result value

The resulted value is calculated by testing the script and corresponds with the value of the VChannel at run time.

Execute

Runs the script.

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Open the VChannel Library Functions window and allows the user to add functions from the library to the script editor.

The script editor contextual menu gives the user quick access to Input Signals and Library Functions.

The VChannel Library Functions window allows the user to add functions from the library to the script editor. The functions are listed in the grid along with their Name, Description and Code properties.

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The VChannel Library function

Functions can be defined and stored in the library using the Function Builder.

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The Function Builder

UI Option

Description

Name

Displays the name of the function.

Description

The function's description.

Code

The code editor. Can define functions or subs.

Functions:

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Subs:

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Add

Adds the function to the library.

Delete

Deletes the selected function from the library.

Save

Saves the changes.

Close

Closes the function library.

Collective Alarm

The Collective Alarms calculation base allow the user to integrate several alarms in a VChannel as a collective alarm. The value of the virtual signal at run time will be the number of active alarms from the Collective Alarms.

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VChannel collective alarms

UI Option

Description

Signal Name

The name of the signal attached to the alarm.

Alarm Name

The name of the alarm.

Add

Opens the Collective Alarms window and allows the user to add alarms to the VChannel.

Remove

Removes the selected alarms.