> For the complete documentation index, see [llms.txt](https://docs.videc.de/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.videc.de/acron-9.3/en/anlagenkonfiguration/prozessanbindung/provider/providerid/treiberauswahl/opc_data-access-client-mit-zeitstempel.md).
# OPC Data Access Client with time stamp
#### Background
The OPC interface driver works with all OPC servers as from OPC version 1.0. Measurement data and service data can be imported. Alerts and messages cannot be imported at present. The ACRON Provider is notified of all changes to the requested data in event-controlled mode and saves them cyclically to the ACRON database.
The *OPCClient driver* imports all the values of the Server in event-controlled mode and sets its own time stamp. This enables ACRON Delta Event recording to be used.
The *OPCClientTS driver* imports all the values of the Server in event-controlled mode and writes them to the ACRON database with the time stamp of the Server.
Note
ACRON Delta Event recording cannot be used. So this driver should only be used when you know how many new values the Server will deliver, and how often, and provided that set of values is wanted.
If the value of the tag is equal to ZERO, for import of the service processing pulses ACRON assumes that the unit in question is not running. If the value is any other, ACRON assumes that the unit is running.
#### Syntax of external variable
Name of variable as defined in OPC Server
Note
If you only want to import a single bit from an external variable, place a comma after the variable name and then append the bit number (0-31). To import the values of the 0th bit of the variable `TEST`, enter the external variable as follows: `TEST,0`.
#### Import external variables
1. Set all parameters for the Provider
2. Start the control system
3. Run "Import from control system" in the "External variables" area
Select the variables you want to import into ACRON.
## Driver
### Driver file
Display the name of the selected driver and select a driver from the list of installed drivers
### Version
Version of the driver file
### Interface type
Display the driver interface type
### Data transfer type
Description of the data transfer type
## Driver parameters
### Server name or Server name L
Name of OPC server
Note
If a blank followed by a 'L' is entered after the server name, ACRON interprets the server time stamps in local time.
### Type
L- the OPC server is running on the local computer.
R- the OPC server is running on the remote computer.
Note
Use the advanced settings of the parameter Type only if problems occur in communication with the OPC server you are using.
#### Syntax of the advanced settings
Connection type Update rate OPCLevel
#### Explanation
**Connection type**
| L | ACRON initially tries to establish an Inproc connection and, if it fails, tries a local connection |
| - | -------------------------------------------------------------------------------------------------- |
| R | ACRON establishes a remote connection and, if it fails, it aborts |
| i | ACRON establishes an Inproc connection and, if it fails, it aborts |
| l | ACRON establishes a local connection and, if it fails, it aborts |
These four prefix letters can be suffixed by a second letter (such as LX):
| | |
| - | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| R | This option can be useful in the case of OPC servers which sometimes forget to notify OPC client of changes to variables. When the option is set, the ACRON OPC Client explicitly queries the server for new variables if it does not hear anything for 60 seconds. |
| X | This option incorporates the previous functionality. The ACRON OPC Client also restarts communication completely if permanent errors occur. So this option can be useful in the case of OPC servers which sporadically hang up. |
#### Update rate
By default, ACRON sets the update rate to 1000 milliseconds, meaning data is delivered by the server to the ACRON OPC Client every second.
You can specify a higher value in milliseconds. If you enter 1000 here, value changes will be delivered not more frequently than once per second.
It may also be useful to enter 0 here, meaning data is delivered by the server to the ACRON OPC Client as far as possible on every value change.
The actual update rate may vary from what you specify, as it is ultimately determined by the server.
#### OPCLevel
If this entry is missing, the ACRON OPC Client decides whether OPC level 1 or 2 is used based on the server properties.
By entering 1 or 2, you can specify the OPC level to be applied.
`l 1000 1`
Meaning: Local connection with update rate of 1000 milliseconds and OPC level 1.
### Node name
Name of the computer on which the OPC server is running.
### User password and domain
(optional)
User name, password and domain name, if accessing the server on a different computer. Separate entries by a blank space.
## Settings
### Polling delay after start
Start of data logging in seconds after the ACRON Provider has successfully established process communication. This is useful, for example, if the opposite party takes some time after a restart to initialize all the variables.
Recommended entry: Depending on the startup duration of the OPC Server, about 10 seconds
### Always display provider window on top
Provider windows are always displayed on top
### Activate test mode
Display a window with diagnostic messages
On startup the ACRON Provider opens a window with diagnostic messages. The log file is stored under the relevant provider name in the ACRON installation path, in the `Log` directory.
Note
As diagnosis mode heavily influences the performance of the application, and the recorded messages can normally only be evaluated by Technical Support, you should only activate it when prompted to do so by Support.
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