Use shm-et340 with SMA Energy meter (SHM1.0)

[hoschult]

Hi,
tried to use your code with my SMA Energy meter (SHM1.0). Seems to be working - at least partly:

DEBU[0019] Received datagram from meter                 
DEBU[0019] Uid: 262816                                  
DEBU[0019] Serial: xxxxxx                           
DEBU[0019] Total W: -7757.2                             
DEBU[0019] Total Buy kWh: 18513.638899999998            
DEBU[0019] Total Sell kWh: 32970.4046                   
INFO[0019] Meter update received: 18513.64 kWh bought and 32970.40 kWh sold, -7757.2 W currently flowing 
DEBU[0019] +-----+-------------+---------------+---------------+ 
DEBU[0019] |value|   L1 	|     L2  	|   L3  	|          
DEBU[0019] +-----+-------------+---------------+---------------+ 
DEBU[0019] |  V  |     1.00 	|     1.00 	|     1.00 	|  
DEBU[0019] |  A  |    -1.70 	|     1.30 	|    -0.70 	|  
DEBU[0019] |  W  |    -1.70 	|     1.30 	|    -0.70 	|  
DEBU[0019] | kWh | 1721346537.27 	| 3285096407.88 	| 4848846278.50 	| 
DEBU[0019] | kWh | 1799534030.79 	| 3363283901.41 	| 4927033772.02 	| 
DEBU[0019] +-----+-------------+---------------+---------------+ 

UID, Serial and 'Total W' are correct; V/A/W seems to be not decoded correctly (neither for any phases). Tried to look at the datagrams to be captured of speedwire multicast: https://github.com/datenschuft/SMA-EM/blob/master/speedwiredecoder.py - However I was not able to translate towards your code....

Are you foresee to implement also the readings of SHM1.0 (SMA Energy meter)? That would be fantastic.... I can offer my help by supporting the tests.

Thanks,
Holger

[hoschult]

there is a guy at victron community stating the following:

I have used your GIT hub code to hack my SMA EM v1 to work on this. There is essentially a 4 byte offset on the decodePhaseChunks.

[hoschult]

... found a explanation for the 4 byte offset; SHM2 takes also grid frequency into account, SHM1 does not. According to a specification of the speedwire datagram (found at https://openwb.de/forum/viewtopic.php?p=51576 ), grid frequency is at position 160-163:

[hoschult]

Got meter working with SMA EM (SHM1); Need to put an offset at decodePhaseChunks in main.go

L1 := decodePhaseChunk(b[156:300]) L2 := decodePhaseChunk(b[300:444]) L3 := decodePhaseChunk(b[444:588])

That's it.... At least for my setup. To do that in a more general way, offset can be determined on the Revision of the EM; Needs to be investigated since which revision frequency (offset) need to be added (or removed).

[brezel1965]

I also have an SMA Energy Meter and my consumption is incorrect. Unfortunately I don't understand how to write this offset in main.go and compile it, maybe someone can provide the modified shm-et340. Thank you Martin

[hoschult]

hi Martin. I compiled you the shm10 binary, see download link attached: https://magentacloud.de/s/EdWHd267ffLLkZf

[buttermaker11111]

Hello Holger,
can you provide the modified shm-et340 again? Under the link is no file anymore.

Thanks
Olaf