App Development for PLC System

Emerold Refractories had approached us on doing application where their was a need for several operators to run one machine. So the issue was well how do we collect data from each operator and keep track of who is doing what. That lead us to decided to develop an app for android that would collect all the data and drop it into the PLC when they start the operation. That way the operator puts their parameters in away from the process in the 2 mile loop they are running in the truck, then when it comes time to run the operation the App delivers the information to the control system. 

During this process we came across a hurdle being that android wouldn’t let us access system ports meaning no ports below 1025 which Modbus TCP/IP is port 502 so that went out the window unless we wanted to develop very specific tablets to the cause and have a detailed setup procedure for each tablet. So we decided to go with Ethernet/IP. So we found out that a Allen Bradley Micro 820 doesn’t use the same convention as the Compact Logix and there was no documentation on the communications at the time. A communication program was dropped into 2 Micro820’s and we set up a MIM attack on the network to sniff the packets both ways.

PLC Talking

With the information collected in the sniffing our app developer was able to identify the differences in the communications and got the app to successfully communicate with the Micro 820.