Hi all I’m still new with raspberry pi and node red so go easy
My project consists of two sensors which are identical (SDS011) and are connected to the pi via usb, to gather results which are displayed on a chart and gauge I’m using the following flow
https://flows.nodered.org/flow/7be04043044e08e1d3ac02da28223fe3
When one of the sensors is connect all works fine, the problem is when I copy the flow for the other sensor I get the problem, instead of just changing the serial port from sensor 1 to tty usb0 and sensor 2 usb1 node red will only read from one sensor.
To overcome this I tried to rename the USB ports and permanently connect the sensors to specific USB ports when doing this I was able to find atty idproduct and idvendor but both values were the same and as no serial number I used the kernels number of the port.
Some progress made is both sensors are now reading the problem now is it looks as though both sensors are trying to feed data into the same graph and gauges
So I’m trying to get all 4 gauges and the two graphs to run
Any help much appreciated please remember don’t get too technical as my knowledge on this is basic 
Cheers