btw, the way to find out how to talk to these is to run gatttool (three 'T's in that word, sigh...)
$ gatttool -b A6:C0:80:E5:84:0C -I
[A6:C0:80:E5:84:0C][LE]> connect
Attempting to connect to A6:C0:80:E5:84:0C
Connection successful
Notification handle = 0x001b value: 24 f0 04 00 00 00
Notification handle = 0x001b value: 24 f0 04 00 00 00
Notification handle = 0x001b value: 24 f0 04 00 00 00
Notification handle = 0x001b value: 24 f0 04 00 00 00
Notification handle = 0x001b value: 24 f0 04 00 00 00
Notification handle = 0x001b value: 24 f0 04 00 00 00
Notification handle = 0x001b value: 24 f0 04 00 00 00
Notification handle = 0x001b value: 24 f0 04 00 00 00
[A6:C0:80:E5:84:0C][LE]> quit
$
that 0x001b is the key. it can be that value or 0x002e.
from what I've seen, just by sniffing the BLE output, is that meters that use 1b are the cm2100b and the ow18e. the two B meters (b35 and b41) use the 2e handle.
the 6 bytes are 99% the same between the meters. I still need to find all the diffs (I think on the clamp meter vs the others, what continuity_open means is what the others see as continuity_closed. some things are not the same, for some reason). but the basics are there and it should be usable for all four of these models.
linux BLE has a habit of getting stuck, for some reason. I found a resetter that you might need to use, if your commands are not working.
$ sudo python3 ./hci-resetter.py --now
Resetting HCI hci0
HCI hci0 has been reset
you can tell if you need that by trying a ble scan:
$ sudo hcitool lescan
Set scan parameters failed: Input/output error
if you see that error, try the resetter.
$ sudo hcitool lescan
LE Scan ...
12:A7:CE:34:9E:47 (unknown)
64:07:F6:96:0A:03 (unknown)
B2:5C:DA:F7:BC:B5 (unknown)
67:15:BB:2D:90:56 (unknown)
C8:69:CD:51:7B:A1 (unknown)
E8:49:8E:26:D1:5C (unknown)
...