I am getting the following error on a Raspberry pi 3 B+ when using the modbus node.
(node:747) UnhandledPromiseRejectionWarning: Error: Port is not open
at fs.write (/home/pi/.node-red/node_modules/@serialport/bindings/lib/unix-write.js:49:25)
at FSReqWrap.wrapper [as oncomplete] (fs.js:509:5)
(node:747) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 3)
(node:747) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
It is strange because this happens on a new Pi Zero W and an older Pi 3B+ but works fine on an older Pi Zero. I have tried older versions of Raspbian and NR, but cannot identfy why the one Zero works
Any help or advice appreciated