RPI serial input from RS232 via MAX232 to Node-Red

Question

I use Node-Red to monitor serial RS232 data from a home automation box. All works fine for a couple of weeks and then the data is no longer seen. I have to reset the RPI to recover from this. I have very little understanding of Linux and don't know if there is a log to point to the problem. It may even be a Node-Red hangup. I don't know how to tackle the problem. Thanks