vb code to download dlg from micrologix1500

[gtatti]

I need to prepare a vb program to download historical data from an AB micrologix 1500 plc.

Does anybody do that.
Who can help me??

 

[fatpup]

Hi, Try getting hold of HOME AUTOMATION BASICS by Tom Leonik, P.E. it's a good place to start.
You will also need logix500 programming software, which they tend to gloss over in the book!

Goodluck..

 

[heathlovell]

Is there a way to do this without having to purchase software to do the communication? Or are you refering to using VBA to control RSLogix?
Thanks for the help,
Heath

 

[KeithMcR]

For data only communications (as described in the first point), you will not nessessarily need the RSLogix, or any other programming software provided you know the data points you want to communicate to, but you will need a communication server capable of either DDE or OPC communications. If however you need at any time to access the PLC program, programming software would be required. You might need to do this even as a measure to improve the efficiency of your application programming (say, by creating a simple flag to indicate data has changed and to cause an upload from your application). Therefore I think its wise to consider at some point you might need this.

For the DDE/OPC data server application, I would suggest the use of RSLinx and employing OPC rather than DDE as the method. If you do feel the need to have the RSLogix programming software available, you will also need RSLinx which is normally bundled anyway. Note however that the RSLinx Lite product (which is normally bundled with RSLogix) will not support OPC/DDE communications.

It's theoretically possible to create you own point to point communications without the need for a comms server but I think the kind of R&D and coding needed to achieve this would far outweigh the cost involved in purchasing somebody elses. I have worked extensively with the RSI product RSLinx and it does work well - although it costs too. However, I know that there are alternatives available - you might want to look at what else is to be found.

With an OPC compliant server application, its easy to create VB code to read and write data to and from the target PLC with various options of how this should be performed (on request, continuous etc.). I have developed several applications which do this and would be happy to share my experiences with anyone interested.