This function is used in Python Scripting.


Writes a value directly through an OPC server connection synchronously. Will return an OPC-UA status code object. You can quickly check if the write succeeded by calling isGood() on the return value from this function.

Client Permission Restrictions

Permission Type: OPC Server Management

Client access to this scripting function is blocked to users that do not meet the role/zone requirements for the above permission type. This function is unaffected when run in the Gateway scope.


system.opc.writeValue(opcServer, itemPath, value)

  • Parameters

String opcServer - The name of the OPC server connection in which the item resides.

String itemPath - The item path, or address, to write to.

Object value - The value to write to the OPC item.

  • Returns

Quality - The status of the write. Use returnValue.isGood() to check if the write succeeded. Refer to the list of writeValue objects.

  • Scope

Gateway, Vision Client, Perspective Session

Code Examples
Code Snippet - Writing to an OPC Value
# This example will write to an OPC Tag that is on a provider called SLCSim
# Declare the server name
server = "Ignition OPC UA Server"

# Declare the Tag path
path = "[SLCSim]_Meta:N7/N7:0"

# Declare the system function parameters
oldQualifiedValue = system.opc.readValue(server, path)
newValue = oldQualifiedValue.getValue() + 1

# Call the system function and print out results
returnQuality = system.opc.writeValue(server, path, newValue)
if returnQuality.isGood():
	print "Write was successful"
	print "Write failed" 

system opc writeValue, opc.writeValue