After a recent reshuffle in equipment rack, I seem to have lost comms to my SDM120 electricity meters.
Would appreciate any pointers on where to begin troubleshooting.
Many thanks,
Welcome back!
First, don’t rely on memory. Go back to the source data and work out what the connections should be, then look at what you have and compare. In the process, check that you haven’t misidentified a cable or a connector, and the right plug really is in the right socket.
If everything still looks correct, check all the cables over the full length, but particularly at the ends, for physical damage, or loose connections. e.g. screw terminals.
Have your USB ports been enumerated in a different order, i.e. your adapter isn’t at the expected address? e.g. /dev/ttyUSB0 is now /dev/ttyUSB1. Likewise the meters’ addresses on the RS485 bus (a moved DIPswitch?)
thanks Robert,
You were right. I’d plugged back into a different USB port. 
Now working again but I lost a few weeks’ data by not checking.
Best, David