Quick Start on Automatic Collection of Plant Data

Whether you are trying to collect data from a DDE IO server or from an OPC IO server, the task can be daunting in the initial stage trying to determine the proper format of the DDE/OPC addresses. You’ve already watched the eSchool lesson QWSchedule – Automating Quality Window data collection and you know that the first step is filling in the Input File property of each field in your application that will communicate to the outside and collect a tag value from a device. We’ve seen many users jump right in and blindly enter hundreds of tags into their application, click on the Add button, and literally wait many minutes only to find out that all of their addresses were wrongly formatted. They would then have to go back to QWAdmin, change all of the tags slightly and try again until they have a successful read. There is a better way …

If you download the following utility called QWTestIO.exe and save the program into the folder where QW 50 was installed (C:/Program Files(x86)/Busitech/QW50 – 64 bit or C:/Program Files/Busitech/QW50  – for all else)

Navigate to your QW50 installation directory and select QWTestIO.exe andthe following screen will be displayed:

At this point you would enter your DDE or OPC address and then click on the Read Value button to attempt to read the tag value. Here is an example of an OPC address being entered:

If there is a syntax error in your address, you will get back Communication Error message. You would then try to correct the syntax and simply try again. This process is much simpler and much less time consuming than doing the full cycle mentioned above. Once you have valid addresses, you can simply highlight them and copy and paste them into QWAdmin.

The Write Value button is there in case you need to send a value to your device. Be very careful with this function as sending a value to the wrong address could play havoc on your production line.

Note that you are not limited to only DDE: and OPC: addresses. If you like, you could specify a full path name to a QW Input File and read the value contained in it.

Modifying the value and then clicking on the Write Value button would write that value back to the IO file. This brings up another trick: if you have a field in an application that you would like to have a constant value defaulted all of the time, one way would be to set the Input File property and the Output File property to the exact same filename, then save the changes, go into Quality Window and Add a dummy record with the constant value entered and click Save to have the value written to the Output File. But if you leave the Output File property as is, then if a user decides to change the value on one of the records, that value will then become the new default value until changed again. In many cases, this can be exactly the functionality you desire, but in some cases, you do not want the constant value to ever change so you would need to remove the Output File property. Using this tool for the latter case, you would only need to specify the Input File, use the tool to write your constant value to the Input File, and you are done.

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