OPC Communication with Rockwell System
Here we are Operating Rockwell System from our xA through OPC Communication..Will it create any issue if the same OPC Tags of the Rockwel System have Write permissions from our xA sytem and Rockwel System.For Example a Selection Button with tag [ROCKWELL]Fan_Sel is being written from our System and also Rockwell System.
Issue i am facing is that without giving write Operation from neither of the system, the value of the variable is fluctuating on its own and if i disable Property Transfer for Write the issue is not there.
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You must find a method to semaphore the two systems from being able to send simultaneous orders or face the problem of "who is last at the ball governs it's trajectory"
Property Transfer should not be needed. If Rockwell is uploaded to 800xA as Generic OPC network, why transfer?
One method could be if 800xA "post" each order in a "sandbox" at Rockwell side and that some logic on Rockwell side decides which system takes precedence.
In 800xA we have features like the Lock Server and Point Of Control to govern who "has the cue" and who has not. Both anticipate all writers on 800xA side so it cannot be used when other party is at unknown location.
For an 800xA Push Button on an operator display - this is a "Write Once" operation.
You do not say what your Rockwell HMI is, but presumably it is RSView ? Again, an operator pushbutton on a display should be "Write Once"
So for operator push buttons on an HMI, the last button pushed, sets the value in the controller.
However, if you are using a property transfer, then the transfer will continuously write a value to the tag depending on the update and refresh rates you configured. See Stefan's answer to understand how this will affect your system.
If all you are trying to do is use an operator graphic in both the RSview and 800xA systems then yes this will ~probably~ work ( but no guarantees - you are on your own here). If you try to use property transfer, then its likely not going to work.