Is it possible to send one command to measure to all devices connected instead of sending multiple separated commands? about pzem-004t-v30 HOT 2 CLOSED

PZEM's are continuously measuring all parameters, not on command request, so it won't make any difference.

from pzem-004t-v30.

Exactly as @vortigont said, the sensors measure continuously in background and sending the read command only samples the current values from the registers. If you use all the PZEMs on one bus, there is no way to sample all at the same time as you can't have multiple parallel interactions on one bus.

The only solution would be to split the PZEMs to different physical buses. However again, in terms of energy, this would not make much difference as the sensors are anyways keeping their own state in the background. For voltage and current I would anyways not trust the synchronization that you get the measurement values at the precise instant of sending the command (due to averaging etc going on in the background)

So in conclusion I would not worry about it too much.

from pzem-004t-v30.