IO Digital Data Tag

Introduction

The IO Digital Data Tag Digital Data Tag Icon maps two state digital tag to an external data source.

Configuration Properties

The IO Digital Data Tag supports the configuration properties of the Digital Data Tag plus these properties:

Property Type Version Description
AllowControls BOOL 3.12 Whether Fernhill SCADA can send controls from this tag to the data source.
IODataSource Reference 3.12 A reference to another tag that provides the external data for the tag.
IOItemName WSTRING 3.12 The data item within the external data source.
RawValueInvert BOOL 3.12 Whether the raw value is inverted with respect to the tag state.

AllowControls

The AllowControls property controls access to the WriteValue Tag Command.

When AllowControls is FALSE, access to the WriteValue tag command is blocked. This prevents any user, or program, sending control requests to the data source from this tag. The default value is FALSE to follow security best practice of deny by default.

Even when AllowControls is TRUE, an operator requires the Write User Privilege to send controls to the data source.

For an operator to send a control to the data source, both of these conditions must be true:

IODataSource and IOItemName

The IODataSource field specifies the external data source for the tag. The IOItemName field specifies the item of data within the data source. The format of the IOItemName field depends on what type of tag is configured in the IODataSource field. This table summarises which tags you can use for the IODataSource field, and the corresponding format of the IOItemName field.

IODataSourceIOItemName
Allen Bradley PLC A string formatted with the Allen Bradley PLC Data Address Format.
Allen Bradley Register Block A string formatted with the Allen Bradley PLC Data Address Format.
CSV File The location of the variable in the file using spreadsheet notation, for example B5 represents row 5 and column 2.
Idec Micro PLC A string formatted with the Idec Micro PLC Data Address Format.
Idec Micro Register Block A string formatted with the Idec Micro PLC Data Address Format.
Mitsubishi Melsec PLC A string formatted with the Mitsubishi Melsec PLC Data Address Format.
Mitsubishi Melsec Register Block A string formatted with the Mitsubishi Melsec PLC Data Address Format.
Modbus PLC Device A string formatted with the Modbus PLC Data Address Format.
Modbus Register Block A string formatted with the Modbus PLC Data Address Format.
MQTT Connection A string formatted with the MQTT IOItemName Format.
ODBC Query The location of the result in the result set using spreadsheet notation, for example B5 represents row 5 and column 2.
Omron PLC using FINS A string formatted with the Omron PLC Data Address Format.
Omron PLC using Host Link A string formatted with the Omron PLC Data Address Format.
Omron Register Block A string formatted with the Omron PLC Data Address Format.
OPC Server Connection The OPC item name.
Random Generator A property name of the random generator.
Siemens S7 Ethernet PLC A string formatted with the Siemens S7 PLC Data Address Format.
Siemens S7 Serial PLC A string formatted with the Siemens S7 PLC Data Address Format.
Siemens S7 Memory Block A string formatted with the Siemens S7 PLC Data Address Format.
SNMP Agent The OID of the variable in the SNMP Agent.

RawValueInvert

The RawValueInvert property configures whether the raw IO value is inverted with respect to the tag value. When enabled, the inversion applies both to data read from the IO device and also to controls to the IO device.

Dynamic Properties

The IO Digital Data Tag supports the dynamic properties of the Digital Data Tag.

Tag Commands

The IO Digital Data Tag supports tag commands of the Digital Data Tag plus these tag commands:

Tag Command Version Description
WriteValue 3.12 Writes a new value to the data source via the I/O tag.

Relationships to Other Tag Types

The IO Digital Data Tag builds on the features of these tag types:

Further Information

Digital Data Tag

To learn about properties common to all digital tags.

Core Data Driver

To learn about the Core Driver.

Glossary

For the meaning of terms used in Fernhill SCADA.