Connect IoT - OPC DA Driver#
OPC Data Access (OPC DA) is a group of client-server standards that provides specifications for communicating real-time data from data acquisition devices. The specifications focus on the continuous communication of data.
Data Types#
These are the supported specific data types:
| Name | Description |
|---|---|
| VT_UI1 | Unsigned Integer 1 byte |
| VT_UI2 | Unsigned Integer 2 bytes |
| VT_UI4 | Unsigned Integer 4 bytes |
| VT_UI8 | Unsigned Integer 8 bytes |
| VT_I1 | Signed Integer 1 byte |
| VT_I2 | Signed Integer 2 bytes |
| VT_I4 | Signed Integer 4 bytes |
| VT_I8 | Signed Integer 8 bytes |
| VT_R4 | Real Number 4 bytes |
| VT_R8 | Real Number 8 bytes |
| VT_CY | Complex Number |
| VT_DECIMAL | Decimal Number |
| VT_BOOL | Boolean value |
| VT_BSTR | String value |
| VT_DATE | Date and Time value |
Protocol Parameters#
The protocol supports the following parameters, used to define the communication parameters, as well as the expected behavior of the driver:
| Name | Type | Possible Values | Default Value | Description |
|---|---|---|---|---|
| serverName | String | "" | Computer where the OPC DA server is installed | |
| progId | String | "" | Name of ProgId to connect | |
| domain | String | "" | Domain of the user to login | |
| userName | String | "" | User name to login | |
| password | String | "" | Password of the user to login | |
| allowBadValues | Boolean | False | Should BAD values be accepted in events | |
| defaultDataSource | Enum | Device Cache | Device | DataSource to use as default |
Extended Parameters#
Property#
| Name | Type | Possible Values | Default Value | Description |
|---|---|---|---|---|
| dataSource | Enum | Device Cache | Device | DataSource to get the value |
| allowBadValues | Boolean | False | Should BAD values be accepted |
Event#
| Name | Type | Possible Values | Default Value | Description |
|---|---|---|---|---|
| refreshRate | Integer | 1000 | Interval to validate if data changed | |
| triggerDelay | Integer | 0 | Interval to wait before triggering the event. Useful when tag values are out of sync with the trigger tag |
Event Property#
| Name | Type | Possible Values | Default Value | Description |
|---|---|---|---|---|
| isTrigger | Boolean | True | Trigger the event when the value changes |
Remarks/Behavior#
- When an event has more than one property with the
isTriggerflag:- It will be triggered every time any of the properties value changes.
- The value of the other properties will be requested at that time.
- It is possible to have multiple triggers with the same set values (because they have not changed). If this behavior is not intended, separate into multiple events each one with it's own trigger set.
- When an event has no property with the
isTriggerflag, it will never be triggered.