Template library for reading SDM120 SDM220 SDM630 Modbus Energy meters.

SECTIONS:

1. INTRODUCTION

2. SCREENSHOTS

3. INITIALIZING

4. READING

5. DEBUGING

6. CREDITS

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Introduction:

This library allows you reading SDM module(s) using:

• Hardware Serial (recommended option, smallest number of reads errors) or
• Software Serial (library for ESP8266 https://github.com/plerup/espsoftwareserial)

you also need rs232<->rs485 converter:

• with automatic flow direction control (look at images below) or
• with additional pins for flow control, like MAX485
  (in this case MAX485 DE and RE pins must be connected together to one of esp pin
  and this pin must be passed when initializing the library)

Tested on Wemos D1 Mini with Arduino IDE 1.8.3-1.9.0b & ESP8266 core 2.3.0-2.4.1

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Screenshots:

live page example (extended) screenshot

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Initializing:

//lib init when Software Serial is used:
#include <SDM.h>
//      ______________________baudrate
//     |    __________________rx pin
//     |   |    ______________tx pin
//     |   |   |    __________dere pin(optional for max485)
//     |   |   |   |
SDM<4800, 13, 15, 12> sdm;

//lib init when Hardware Serial is used:
#define USE_HARDWARESERIAL
#include <SDM.h>
//      ______________________baudrate
//     |    __________________dere pin(optional for max485)
//     |   |    ______________swap hw serial pins from 3/1 to 13/15(default false)
//     |   |   |
SDM<4800, 12, false> sdm;

NOTE: when GPIO15 is used (especially for swapped hardware serial):
some converters (like mine) have built-in pullup resistors on TX/RX lines from rs232 side,
connection this type of converters to ESP8266 pin GPIO15 block booting process.
In this case you can replace the pull-up resistor on converter with higher value (100k),
to ensure low level on GPIO15 by built-in in most ESP8266 modules pulldown resistor.

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Reading:

List of available registers for SDM120/220/630:
https://github.com/reaper7/SDM_Energy_Meter/blob/master/SDM.h#L36

//reading voltage from SDM with slave address 0x01 (default)
//                                      __________register name
//                                     |
float voltage = sdm.readVal(SDM220T_VOLTAGE);

//reading power from 1st SDM with slave address ID = 0x01
//reading power from 2nd SDM with slave address ID = 0x02
//useful with several meters on RS485 line
//                                      __________register name
//                                     |      ____SDM device ID  
//                                     |     |
float power1 = sdm.readVal(SDM220T_POWER, 0x01);
float power2 = sdm.readVal(SDM220T_POWER, 0x02);

NOTE: if you reading multiple SDM devices on the same RS485 line,
remember to set the same transmission parameters on each device,
only ID must be different for each SDM device.

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Debuging:

Sometimes readVal return NaN value (not a number),
this means that the requested value could not be read from the sdm module for various reasons.

Please check out open and close issues, maybe the cause of your error is explained or solved there.

The most common problems are:

• weak or poorly filtered power supply / LDO, causing NaN readings and ESP crashes
  reaper7#13 (comment)
  reaper7#13 (comment)
  reaper7#8 (comment)
  
• faulty or incorrectly prepared converter
  reaper7#16 (comment)
  
• faulty esp module
  reaper7#8 (comment)
  
• many users report that between each readings should be placed delay(50);
  reaper7#7 (comment)
  (I did not observe such problems using the HardwareSerial connection)
  
• using GPIO15 without checking signal level (note above)
  reaper7#17 (comment)
  reaper7#13 (comment)
  reaper7#13 (comment)
  

You can get last error code using function:

//get last error code
//                                      __________optional parameter,
//                                     |          true -> read and reset error code
//                                     |          false or no parameter -> read error code
//                                     |          but not reset stored code (for future checking)
//                                     |          will be overwriten when next error occurs
uint16_t lasterror = sdm.getErrCode(true);

//clear error code also available with:
sdm.clearErrCode();

Errors list returned by getErrCode:
https://github.com/reaper7/SDM_Energy_Meter/blob/master/SDM.h#L103

You can also check total number of errors using function:

//get total errors counter
//                                       _________optional parameter,
//                                      |         true -> read and reset errors counter
//                                      |         false or no parameter -> read errors counter
//                                      |         but not reset stored counter (for future checking)
uint16_t cnterrors = sdm.getErrCount(true);

//clear errors counter also available with:
sdm.clearErrCount();

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Credits:

👍 ESP SoftwareSerial library by Peter Lerup (https://github.com/plerup/espsoftwareserial)
👍 crc calculation by Jaime García (https://github.com/peninquen/Modbus-Energy-Monitor-Arduino)
👍 new registers for SDM120 and SDM630 by bart.e (https://github.com/beireken/SDM220t)

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2016-2018 Reaper7

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