I am using a RAK5802 to communicate with an RS485 sensor probe. I have everything working great and I am able to pull the data from the sensor. However after a period of time, I begin to experience timeouts on the RS485 side. I’ve replaced boards, and wisblock items, and pretty much everything but this still randomly happens. Today once I got the failure notice, I decided to bring the device in and touch a ground to the ground pin on the RS5802 quick attach block and then my device started working again. Aside from the probe the entire setup is RAK Wisblock devices. I am utilizing the RAK19013 for the Solar charging and a 3.7 LiPo pouch battery. I am using the RAK19002 to power the sensor probe as it needs 10+ volts to operate.
I suppose my questions are, has anyone else had an issue where a ground was needed? Is the RAK19013 producing noise in the power plane that might be skewing the differential signaling of the RS485 chip? Is there a way to emulate ground without needing a ground? Does the RAK19002 GND meet with the rest of the GND plane on the board? Since the VCC and GND for the probe are coming from the RAK19002, do I need to find a way to link the GND back to the RAK5802 pin?
Probe device is a 4-pin RS485 with VCC, GND, RS485-A and RS485-B.
VCC and GND connect to RAK19002.
RS485-A and RS485-B connect to the quick attach block on the RAK5802.
Everything thing else is running like a champ, the device still connects via lorawan, even with failed values. Again, simply touching a ground to the ground pin on the quick attach block suddenly fixed the probe not working so I’m thinking this may be a electrical issue/signal issue on the board components.
Pig