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Disclaimer: This document is written in the hope that you can utilize for your own education to gain knowledge of PLC systems (should you decide to utilize this document). Although I believe the information in this document to be accurate, it is YOUR responsibility to verify this information before implementing it in any way, especially when damage to personnel or equipment could result. By continuing to read this document, you agree to hold no one who writes, modifies, or distributes this document liable in any way (even negligence). Due to the wide variety of plant applications, some of the examples in this document may be prohibited at your location, or could cause damage to equipment, or harm personnel.
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Connecting to a Spreadsheet using DDE


Using a spreadsheet such as OpenOffice.org Calc, or Excel, you can create a DDE (Dynamic Data Exchange) link through RSLinx. This can be useful to replace the custom data monitor feature that existed in RSLogix 5 and 500. Using a spreadsheet has a few advantages over the custom data monitor, such as the ability to perform calculations, create charts and graphs, multiple columns of data, etc... This tutorial assumes you already have a running driver and are connected to the PLC using professional version of RSLinx.


  1. The first step in creating the link is to open RSLinx communication server.





  1. Open the RSWho screen, and locate your processor. This can be a PLC-5, SLC-500, ControlLogix, etc... The same procedure applies to each family of processors. For this example, we will use the PLC-5





  1. Next, you will want to determine which driver your processor is under. For this example, I will use the TCP Driver since I'm going through a gateway. You may use the ethernet driver, or DF1 driver as well. Expand the driver, and locate your processor. (Note: If you are connecting to a ControlLogix system over Ethernet, you will need to expand the Ethernet driver, drill through the ethernet module, and across the backplane to find the processor.)





  1. Once, you have found the processor, right click the processor and choose 'Configure new DDE/OPC Topic'.





  1. Next, type the name of your topic. In this example, the topic will be named 'MyTopic', and the processor I am pointing this topic to is already highlighted.





  1. Click the 'Data Collection' Tab. Change the Poll rate to 100ms for this example to improve the update time of our link. (Note: In most situations, you want to keep the poll time as slow as possible to reduce load on the network.)







  1. Press 'Apply'.





  1. You will be asked to update the topic. Click 'Yes'.





  1. Now click 'Done'. (Do not click Clone!)





  1. Next, open your spreadsheet program.





  1. In a cell of your spreadsheet, enter the formula in the following format:


=RSLinx|MyTopic!'DataTableAddress'


  1. The cell in your spreadsheet should now be displaying the value of the data table (or tag) that you chose to view.