Many controls manufactures are combining HMI operator stations with PLC in a single package solution.
This solution is very attractive for reasons that may not initially be obvious. Consider how large ware house controls system were designed in the 1980’s. These were the days of large centralized control systems. It was just easier to work with a single control program than with the headaches of programming multiple processors.
REMOTE MONITOR OF MACHINE PRODUCTION VALUES
It is much easier today to place the PLC in smaller zones in a centralized control solution. Ethernet communication has made it easy to monitor and program distributed small control systems. Part counters, rate meters, temperature sensors are now smart devices, fully networked to the factory network.
NO NEED FOR SOFTWARE TO INSTALL A NEW CONTROL
There is an important advantage to many of these small HMI/PLC solutions. Most of these control platforms support SD (solid state) of CF (compact flash) for operating system and program backup. In the event a control fails, it is only necessary to place the memory storage in the new control and power up the system.