I just now re-read this for 10th time and I just want to clear this up in case there is a misunderstanding…
There is only a conflict if you have the same serial port configured in the PAC Control Strategy and are using commands in the strategy to address that comm port.
If so, you have two programs, PAC Control strategy and Node-RED, addressing the same serial port and you will not get the results you expect in either.
Running PAC Control and Node-RED at the same time is not a problem.
Put more simply, you would see the exact same behavior with PAC Control and Node-RED both controlling the same digital output point… It could be done, but you better know what you are doing. < grin >
The method @philip points out is a great solution as you will only have Node-RED accessing and controlling the serial data via the hardware module, but you will have the exact serial data in PAC Control to do what it needs. (Flip Philips solution around if you need PAC Control to write some data back out the port at any time).