Before using this driver in the PROMOTIC application it is highly recommended to read the chapter:
- Usage of this driver requires purchase of the PmOPC licence
. With the freeware version PmFree
, or when developing the application (with development environment
for testing purposes), this component is always functional.
The communication description by means of the PmaCommGroup object
objects can be used for this driver.
The variables in the PmaCommGroup
object (or even better the variables in the PmaData
object with ExtComm
data extension) can be of arbitrary number, type and order. The driver uses optimalised internal communication messages for reading the data from the device.
All variables are read (if the "Data refresh enabled
" configurator is checked). When writing into the variable, only the single value is sent (if the "Auto send when writing to item
" configurator is checked). Refresh of values of variables registered in the PmaCommGroup object:
While being initialized, the driver registers all its variables to the OPC server (OPC system message CreateMonitoredItems
) and informs the server about the requested update rate based on the settings of the "Communication refresh rate [ms]
The the driver sends request to be updated when the values of these variables change (OPC system message PublishRequest
). The OPC server than, on change of the variable, (or if there is no change, the rate defined in the "Communication refresh rate [ms]
" configurator is used) sends a message containing information regarding all changed variables (OPC system message PublishResponse
After receipt of this message, the driver immediately sends the PublishRequest
message again. This way the values of the variables of the PmaCommGroup
object are being updated with defined period Communication refresh rate [ms]
. Description of the "ItemID" configurator
is the text identifier of the item that is used for addressing the value in the device. The "ItemID
" configurator tells the driver how to receive or send the item value.
The text can be written manually, or it can be assembled in the window opened by the button to the right of the configurator. Macro expression
can be used for input (it is evaluated after starting the application).
identifier may look like for example "ns2,str,xxxx
- ns2: Specifies the ns=namespace of the OPC-UA server where the variable belongs (0, 1, 2 ...).
: Specifies the type of variable identifier.
str = The identifier of the variable is a text string.
nmb = The identifier of the variable is a number.
- xxxx: Variable identifier. This text depends only on the OPC-UA server.
| Time reading type||Defines whether the value time is also read along with the variable value from the OPC-UA server. |
If the time is read then this time is saved into the PmVar.TimeSource property.
No - The time value will not be read.
Source - The source time will be read, i.e. the time that the OPC-UA server read from the connected device (if the server is able to read such time).
Server - The time of the value reading by the OPC-UA server will be read.