Below is a link to a great whitepaper about the learning path for PLC network Communication to PC (HMI SCADA), to the Smartphone (cloud). More accurately PLC to OPC/SQL to Smartphone App or HTML5. Includes network security advice for the stages alogn the way too. Start with PLC network and communication protocols and methods, then expand to HMI-SCADA, to SQL (and brand specific topics like RSLinx OPC server), Excel OPC client, HTML5 and your ready for Smartphone.
Below is 1 of the 4 videos in a new interactive training video course about Networking Allen Bradley PLC and PACs. Besides the 4 interactive training videos in this PLC networking course, there is also a link below for free powerpoint with instructor notes and a more detailed online quiz.
For full free PLC networking course, see http://bin95.com/PAC-PLC-Networking-Basics.htm