Easy to use C library with a low memory footprint to parse SML messages (based on BSI TR-03109-1) byte by byte from smart meters. It's designed to be lightweight and efficient and has a small memory footprint, making it suitable for use on embedded systems or other devices with limited memory resources.
The library will control the last CRC value to check if the received data is correct. On any error, the parser will reset and wait for valid data. This allows to start parsing at any time. For example, a half received message is discarded. The library allows you to register handlers to process the received information. This feature allows you to easily process the data in your application without having to handle the low-level details of parsing the SML messages.
It's actively maintained and has already been used in various projects with meters from EMH, EFR, EasyMeter, etc.
The API is described in sml.h via doxygen comments.
| Directory | Description |
|---|---|
| arduino | Loops through static data and outputs debug messages to serial |
| arduino_serial | Reads data from Arduino Pin 8 and outputs debug to serial |
| esp32_lora | Forward energy usage to LoraWAN (The Things Network) |
| esp32_m5stack_sender | Use m5stack to produce a message for testing |
| esp32_receiver | Receive messages and show infos on a display |
| native | Test library locally |
The easiest way to test the library would be over the native example.
void Manufacturer() {
smlOBISManufacturer(manuf, MAX_STR_MANUF);
}
void PowerT1() {
smlOBISWh(T1Wh);
}
void PowerSum() {
smlOBISWh(SumWh);
}
SMLHandler SMLHandlers[] = {
{{ 0x81, 0x81, 0xc7, 0x82, 0x03, 0xff }, &Manufacturer}, /* 129-129:199.130.3*255 */
{{ 0x01, 0x00, 0x01, 0x08, 0x01, 0xff }, &PowerT1}, /* 1- 0: 1. 8.1*255 (T1) */
{{ 0x01, 0x00, 0x01, 0x08, 0x00, 0xff }, &PowerSum}, /* 1- 0: 1. 8.0*255 (T1 + T2) */
{{ 0, 0 }}
};
int main () {
int i = 0, iHandler = 0;
unsigned char c;
sml_states_t s;
for (i = 0; i < ehz_bin_len; ++i) {
c = ehz_bin[i];
s = smlState(c);
if (s == SML_START) {
/* reset local vars */
manuf[0] = 0; T1Wh = -3; SumWh = -3;
}
if (s == SML_LISTEND) {
/* check handlers on last received list */
for (iHandler=0; SMLHandlers[iHandler].Handler != 0 &&
!(smlOBISCheck(SMLHandlers[iHandler].OBIS)); iHandler++);
if (SMLHandlers[iHandler].Handler != 0) {
SMLHandlers[iHandler].Handler();
}
}
if (s == SML_UNEXPECTED) {
printf(">>> Unexpected byte! <<<\n");
}
if (s == SML_FINAL) {
printf(">>> FINAL! Checksum OK\n");
printf(">>> Manufacturer.............: %s\n", manuf);
printf(">>> Power T1 (1-0:1.8.1)..: %.3f kWh\n", T1Wh);
printf(">>> Power T1+T2 (1-0:1.8.0)..: %.3f kWh\n\n", SumWh);
}
}
}If debug mode via SML_DEBUG (see examples/native/platformio.ini) is enabled, the SML data is displayed in a tree like structure.
START
LISTSTART on level 1 with 6 nodes
Data 6 (length = 6, octet string): 00 0C 04 08 87 2D
Data 5 (length = 1, unsigned int): 00
Data 4 (length = 1, unsigned int): 00
LISTSTART on level 2 with 2 nodes
Data 2 (length = 2, unsigned int): 01 01
LISTSTART on level 3 with 6 nodes
Data 6 (empty)
Data 5 (empty)
Data 4 (length = 6, octet string): 00 0C 06 9E 2D 0F
Data 3 (length = 10, octet string): 06 45 4D 48 01 00 1D 46 15 CA
Data 2 (empty)
Data 1 (empty)
LISTEND
back to previous list
back to previous list
Data 2 (length = 2, unsigned int): 2B 8E
End of block at level 1
back to previous list
LISTSTART on level 1 with 6 nodes
Data 6 (length = 6, octet string): 00 0C 04 08 87 2E
Data 5 (length = 1, unsigned int): 00
Data 4 (length = 1, unsigned int): 00
LISTSTART on level 2 with 2 nodes
Data 2 (length = 2, unsigned int): 07 01
LISTSTART on level 3 with 7 nodes
Data 7 (empty)
Data 6 (length = 10, octet string): 06 45 4D 48 01 00 1D 46 15 CA
Data 5 (empty)
LISTSTART on level 4 with 2 nodes
Data 2 (length = 1, unsigned int): 01
Data 1 (length = 4, unsigned int): 06 9E FA 83
LISTEND on level 4
back to previous list
LISTSTART on level 4 with 7 nodes
LISTSTART on level 5 with 7 nodes
Data 7 (length = 6, octet string): 81 81 C7 82 03 FF
Data 6 (empty)
Data 5 (empty)
Data 4 (empty)
Data 3 (empty)
Data 2 (length = 3, octet string): 45 4D 48
Data 1 (empty)
LISTEND
back to previous list
LISTSTART on level 5 with 7 nodes
Data 7 (length = 6, octet string): 01 00 00 00 09 FF
Data 6 (empty)
Data 5 (empty)
Data 4 (empty)
Data 3 (empty)
Data 2 (length = 10, octet string): 06 45 4D 48 01 00 1D 46 15 CA
Data 1 (empty)
LISTEND
back to previous list
LISTSTART on level 5 with 7 nodes
Data 7 (length = 6, octet string): 01 00 01 08 00 FF
Data 6 (length = 2, unsigned int): 01 82
Data 5 (empty)
Data 4 (length = 1, unsigned int): 1E
Data 3 (length = 1, signed int): 03
Data 2 (length = 5, signed int): 00 00 00 1C 46
Data 1 (empty)
LISTEND
back to previous list
LISTSTART on level 5 with 7 nodes
Data 7 (length = 6, octet string): 01 00 01 08 01 FF
Data 6 (empty)
Data 5 (empty)
Data 4 (length = 1, unsigned int): 1E
Data 3 (length = 1, signed int): FF
Data 2 (length = 8, signed int): 00 00 00 00 07 5B CD 15
Data 1 (empty)
LISTEND
back to previous list
LISTSTART on level 5 with 7 nodes
Data 7 (length = 6, octet string): 01 00 01 08 02 FF
Data 6 (empty)
Data 5 (empty)
Data 4 (length = 1, unsigned int): 1E
Data 3 (length = 1, signed int): 03
Data 2 (length = 5, signed int): 00 00 00 1C 46
Data 1 (empty)
LISTEND
back to previous list
LISTSTART on level 5 with 7 nodes
Data 7 (length = 6, octet string): 01 00 0F 07 00 FF
Data 6 (empty)
Data 5 (empty)
Data 4 (length = 1, unsigned int): 1B
Data 3 (length = 1, signed int): FF
Data 2 (length = 4, signed int): 00 00 2F 65
Data 1 (empty)
LISTEND
back to previous list
LISTSTART on level 5 with 7 nodes
Data 7 (length = 6, octet string): 81 81 C7 82 05 FF
Data 6 (empty)
Data 5 (empty)
Data 4 (empty)
Data 3 (empty)
Data (length = 48): FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
Data 2 (empty)
Data 1 (empty)
LISTEND
back to previous list
back to previous list
Data 2 (empty)
Data 1 (length = 2, unsigned int): B9 3F
LISTEND on level 3
back to previous list
back to previous list
End of block at level 1
LISTSTART on level 2 with 6 nodes
Data 6 (length = 6, octet string): 00 0C 04 08 87 31
Data 5 (length = 1, unsigned int): 00
Data 4 (length = 1, unsigned int): 00
LISTSTART on level 3 with 2 nodes
Data 2 (length = 2, unsigned int): 02 01
LISTSTART on level 4 with 1 nodes
Data 1 (empty)
LISTEND
back to previous list
back to previous list
Data 2 (length = 2, unsigned int): 6A 53
End of block at level 2
back to previous list
back to previous list
End of block at level 0
Received checksum: C6E8
Calculated checksum: C6E8
>>> FINAL! Checksum OK
>>> Manufacturer.............: EMH
>>> Power T1 (1-0:1.8.1)..: 12345678.900 Wh
>>> Power T1+T2 (1-0:1.8.0)..: 7238000.000 Wh
The following sites provided a lot of helpful information to me.
- https://wiki.volkszaehler.org/software/obis
- https://wiki.volkszaehler.org/software/sml
- https://www.stefan-weigert.de/php_loader/sml.php
- https://github.com/devZer0/libsml-testing
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