system.opc.readValue
This function is used in Python Scripting.
Description​
Reads a single value directly from an OPC server connection. The address is specified as a string, for example, [MyDevice]N11/N11:0The object returned from this function has three attributes: value, quality, and timestamp. The value attribute represents the current value for the address specified.
The quality attribute is an OPC UA status code. You can easily check a good quality vs a bad quality by calling the isGood() function on the quality object. The timestamp attribute is Date object that represents the time that the value was retrieved at.
Client Permission Restrictions​
This scripting function has no Client Permission restrictions.
Syntax​
system.opc.readValue(opcServer, itemPath)
Parameters​
| Type | Parameter | Description |
|---|---|---|
| String | opcServer | The name of the OPC server connection in which the item resides. |
| String | itemPath | The item path, or address, to read from. |
Returns​
QualifiedValue - A QualifedValue object that contains the value, quality, and timestamp returned from the OPC server for the address specified.
Scope​
Gateway, Vision Client, Perspective Session
Code Examples​
server = "Ignition OPC UA Server"
path = "[SLCSim]_Meta:N7/N7:0"
qualifiedValue = system.opc.readValue(server, path)
print "Value: " + str(qualifiedValue.getValue())
print "Quality: " + qualifiedValue.getQuality().toString()
print "Timestamp: " + qualifiedValue.getTimestamp().toString()