With the jump to All-Grain brewing with an electric HERMS system, I need some way to control it. I’m a controls engineer and work with a ton of Modbus devices for work and decided that I’d like to control/monitor over Modbus. This eliminates a lot of the buttons/switches/indicators, etc. I’d seen some people using PLC’s on the forum and started talking to one of them (Brad) from HomeBrewTalk, who has been awesome.
The main part of electric brewing, is that you need something to control the elements. Most people use PID controllers, or a PLC running PID control loops. In talking to Brad about his advice, he mentioned he had 4 DIN-rail mounted PID controllers. No display, just Modbus RTU control. They’re Watlow MicroDIN controllers and do everything I need and work with RTD or Thermocouple inputs and dr4ive SSRs directly. I bought them from him and started building the panel.
As a means to talk to these, I use an Ethernet gateway from the company I work with, an Obvius Acquisuite. It translates Modbus TCP (Ethernet) to Modbus RTU (RS485). I also started researching ways to visualize the data using some sort of HMI software. After evaluating many solutions, I stumbled across MyScada. It can run on a computer, on an android device, or as a webserver on a Raspberry Pi. I chose to run on the Pi, so I can use any web-enabled device on my network to access the control screens.
So far, the panel will house the 4 controllers, The gateway, the Raspberry Pi, 4 SSRs, a main contactor, E-stop, Keyswitch, fuses and power supplies. An Android tablet will serve as the interface.
I got the PID controllers a couple weeks back and got them working and talking to the MyScada software. It’s really easy to design clean HMI screens. The free version is limited, so I went ahead and bought the license (very reasonable prices). It does full alarming, it logs data (useful for recipe re-creation), can SMS, email on alarm, has user levels and can graph trends/history.
I experimented with a few screens and the first one below is the latest iteration as of today. Also below are some pictures of the panel: