Virtual commissioning

hello,

i am researching about virtual commissioning.
i got to know that virtual commissioning is basically connecting a real PLC with a virtual plant model. integration is through OPC.
OPC recieves values from PLC.
but i din't understand where the PLC is getting values from?.
because at the moment PLC is not connected to Real Plant to receive any sensor or actuator values.

Kindly let me know if i am wrong some where

We do this using a now obsolete product from Rockwell ... RSTestStand. The "process" needs to be modeled in the RSTestStand, then make connections to the PLC. The PLC program will control the modeled process. Once the process is modeled adequately, we can make modifications to the PLC program and validate the code.

It takes a lot of effort, but in a regulated environment where you do not have access to the process to test changes, it is very valuable.

Using this manner, we make coding changes, and queue up a deployment for when an outage can be scheduled and managed.

We did this in two steps:
1) Smoke test and I/O test, where each PLC input was wired to a simulator and internal panel connections, scaling, HMI displays, etc. were verified. Our systems generally had multiple PLCs connected to a comm network. We did the hardwired testing on each PLC and every I/O point one at a time.

2) We would then use a spreadsheet and PC tied to the comm link and all PLCs on the link. The scaling etc. from the individual PLCS would be disabled. We would then use the spreadsheet to push values into the PLCs and verify logic.

Hello, thanks a lot ...but can u explain more about spreadsheet.
as i dont know what it is

MS Excel file for example, containing DDE links or macros related to the PLCs' data tables (tag databases)...a way to write data to the virtual tested PLCs applications...

We use this http://material.sa.online.pt/downloads/Molex/Brochuras/IOSimulation/SST_PICS.PDF

It takes a while to set up but if you are going to use it a lot then it is well worth the time and effort.

Mark

Take a look at simulink http://www.mathworks.com/products/simulink/index.html

This link is to their page on rockwell integration http://www.mathworks.com/programs/rockwell-automation.html