I'm working on a project to automate some machines that are fairly simple... It is essentially a portable machine on a trailer that unwinds cable from a large reel and cuts it into short pieces for recycling.. In an effort to keep cost down I envisioned using a raspberry pi running node red with a touch screen as a HMI I'm using a Click plus PLC that supports MQTT... the problem is the MQTT implementation does not allow reading or writing any IO or storage bits. Automation Direct has a node red module but it is pretty pricey. I saw some videos thought that show their node red has nodes specifically for reading and writing pretty much anything from timers to IO. There is also modbus capability with this plc and you can read and write most anything using it. But it would be so much cleaner if you had those tools from their node red. How big a deal would it be to emulate that.. or possibly convince Automation direct to create a palette for use with raspberry pi version of node red.
it appears the modbus implementation has some issues as well no way in the plc to map modbus IO... I have found a workaround for the MQTT... the PLC writes the MQTT msg to TXT variables one character at a time to TXT1 thru however many characters you have. so you can then do a compare TXT1 to TXT10 in the ladder to set or reset memory locations
