Saving offline metervalues

[VjSargunam]

Hi Matt,
I want to save the offline meter value in the local storage (say in my case in SD card) and update the CMS with this saved meter value data once connection is reestablished between CMS and charger. How to store the offline meter values in local storage? Help me in this regard.

Thanks
VJsargunam

[matth-x]

Hi @VjSargunam,

The long-time storage of the MeterValues operation itself is not supported at the moment. But in case the measurements are used for billing purposes, there is a very similar use case which is supported. The StopTransaction embeds a field "transactionData" which contains a history of metering data which is similar to the MeterValues. Here are the steps to activate it:

• Change the configurations StopTxnSampledData or StopTxnAlignedData so that they contain the desired measurands
• Change Cst_StopTxnDataCapturePeriodic (the Cst_ prefix could be different depending on your version) to true so that the library will not only store the measurands at the begin and end of the transaction, but also periodically in between
• At the moment, the size of the history is limited to only 4 snapshots. To increase it, you need to modify MOCPP_MAX_STOPTXDATA_LEN by hand (will be variable in future)

The primary use case for this is to store signed OCMF data sets which are necessary for public chargers in Germany. But generally it's suitable for any measurement format.

Will it work for you? I can also outline how to extend the operations store so that it also supports MeterValues, but I don't have any plans to add this feature to this repo in near future.

[VjSargunam]

Hi Matt,
As per your suggestion i changed the StopTxnDataCapturePeriodic as shown below
StopTxnDataCapturePeriodic = declareConfiguration(MOCPP_CONFIG_EXT_PREFIX "StopTxnDataCapturePeriodic", true, CONFIGURATION_FN, true, true, true, false);

And after doing remote start and remote stop the transaction how to visualize the saved meter data?. Where to get this stored measurand data?

[matth-x]

The snapshots are stored as files in the OCPP directory. Their naming scheme is sd-X-Y-Z.jsn whereas X is the connectorId, Y is the transaction number (a local transaction key, not the same like the transactionId) and Z is an incrementing number for the snapshot.

They should also be transmitted in the StopTransaction.req if everything works, so you can check the results in the logs.

Please note that declareConfiguration will only fetch the Configuration, but not overwrite its value. The given parameter is just a factory default, in case the config doesn't exist already. To change the config, either use the ChangeConfiguration command in the OCPP server, or change the config value by calling *StopTxnDataCapturePeriodic = true;

[VjSargunam]

Hi Matt,
As you suggested i changed the *StopTxnDataCapturePeriodic value to true. But once i compiled and burn the code in to esp32, the esp32 gets crashed.
I changed the code present in MicroOcpp/Model/Metering/MeteringConnector.cpp like below
//StopTxnDataCapturePeriodic= declareConfiguration<bool>(MOCPP_CONFIG_EXT_PREFIX "StopTxnDataCapturePeriodic", false, CONFIGURATION_FN, true, true, true, false); *StopTxnDataCapturePeriodic = true;
the output is like

[main] Wait for WiFi: ... connected! Guru Meditation Error: Core 1 panic'ed (LoadProhibited). Exception was unhandled. Core 1 register dump: PC : 0x400dbbce PS : 0x00060530 A0 : 0x800fb854 A1 : 0x3ffb24a0 A2 : 0x00000000 A3 : 0x3ffb2578 A4 : 0x3ffc350c A5 : 0x3ffcf780 A6 : 0x00000001 A7 : 0x00000001 A8 : 0x800d9e0a A9 : 0x3ffb2480 A10 : 0x3ffcaf9c A11 : 0x3ffb24d8 A12 : 0x00000001 A13 : 0x3ffcf774 A14 : 0x00000000 A15 : 0x3ffcf780 SAR : 0x00000010 EXCCAUSE: 0x0000001c EXCVADDR: 0x00000022 LBEG : 0x4008a48d LEND : 0x4008a49d LCOUNT : 0xfffffffe Backtrace:0x400dbbcb:0x3ffb24a00x400fb851:0x3ffb2500 0x400ec313:0x3ffb25a0 0x400d7b9b:0x3ffb2630 0x400d7ed1:0x3ffb2660 0x400d31a1:0x3ffb27b0 0x400fff6e:0x3ffb2820 ELF file SHA256: 0000000000000000 Rebooting...

As you mentioned i added the key value to StopTxnSampledData and StopTxnAlignedData and i got the stored data when i initiate stop transaction.req but the values shown were stored by OCPP client only during start and stop transaction not in between.
here is the output
[2,"1000022","StopTransaction",{"meterStop":0,"timestamp":"2023-09-27T09:36:40.056Z","transactionId":409048,"reason":"Remote","transactionData":[{"timestamp":"2023-09-27T09:31:30.015Z","sampledValue":[{"value":" 0.0","context":"Transaction.Begin","measurand":"Energy.Active.Import.Register","location":"Outlet","unit":"Wh"}]},{"timestamp":"2023-09-27T09:36:40.154Z","sampledValue":[{"value":" 0.0","context":"Transaction.End","measurand":"Energy.Active.Import.Register","location":"Outlet","unit":"Wh"}]}

but I can be able to add only one key value like Energy.Active.Import.Register and if try to add more key values like SoC and Temperature it was rejected by the OCPP client. Is there any reason for it to be rejected?

[matth-x]

You still need to declare the configuration before editing it. In the code snippet above, the declaration is commented out and thereby all subsequent writes and reads will be redirected to the NULL pointer and crash. If you revert the code changes and use the OCPP server to send a ChangeConfiguration to enable Cst_StopTxnDataCapturePeriodic, it might be a bit clearer.

Anyway, the StopTx looks already good, except that it only contains the start and stop measurement for now. On the flash storage, there should be two files sd-*.jsn now containing the record.

The OCPP lib rejects unsupported measurands in the selection configs (i.e. StopTxnSampledData). To add support for more measurands, see this example:

https://github.com/OpenEVSE/openevse_esp32_firmware/blob/8c9a482c912005f4c5f0e2d82d2f596e665dd6eb/src/ocpp.cpp#L206-210

[VjSargunam]

Hi Matt,
Thanks got the output. The log shown below
[2,"1000013","StopTransaction",{"meterStop":0,"timestamp":"2023-09-27T10:56:01.556Z","transactionId":409072,"reason":"Remote","transactionData":[{"timestamp":"2023-09-27T10:51:57.171Z","sampledValue":[{"value":" 0.0","context":"Transaction.Begin","measurand":"Energy.Active.Import.Register","location":"Outlet","unit":"Wh"}]},{"timestamp":"2023-09-27T10:52:57.415Z","sampledValue":[{"value":" 0.0","context":"Sample.Periodic","measurand":"Energy.Active.Import.Register","location":"Outlet","unit":"Wh"}]},{"timestamp":"2023-09-27T10:53:57.499Z","sampledValue":[{"value":" 0.0","context":"Sample.Periodic","measurand":"Energy.Active.Import.Register","location":"Outlet","unit":"Wh"}]},{"timestamp":"2023-09-27T10:56:01.648Z","sampledValue":[{"value":" 0.0","context":"Transaction.End","measurand":"Energy.Active.Import.Register","location":"Outlet","unit":"Wh"}]}]}]

[matth-x]

Thank you for the feedback. Feel free to reopen if you have follow-up questions.

[VjSargunam]

Hi Matt,
As per your instruction i added this peace of code in the setup function in order to add more key values to StopTxnSampledData and StopTxnAlignedData.
MicroOcpp::configuration_init(filesystem); MicroOcpp::declareConfiguration<const char*>( "MeterValuesSampledData", "Power.Active.Import,Energy.Active.Import.Register,Voltage,Current.Import,SoC,Temperature"); MicroOcpp::declareConfiguration<const char*>( "StopTxnSampledData", "Power.Active.Import,Energy.Active.Import.Register,Voltage,Current.Import,SoC,Temperature"); MicroOcpp::declareConfiguration<const char*>( "StopTxnAlignedData", "Power.Active.Import,Energy.Active.Import.Register,Voltage,Current.Import,SoC,Temperature"); MicroOcpp::declareConfiguration<bool>( "AO_PreBootTransactions", true);

I works correctly when i start and stop the transaction immediately but when i prolong the charging session and initiate stop transaction means the ESP get stuck it is not responding afterwords and status of the charger still remains charging and is not change back to available. I attached the log below.

[2,"b62a56f9-6f22-4214-b7c5-5366043372f0","RemoteStopTransaction",{"transactionId":409896}] [2,"1000016","MeterValues",{"connectorId":1,"transactionId":409896,"meterValue":[{"timestamp":"2023-09-29T10:19:04.080Z","sampledValue":[{"value":" 0.0","context":"Sample.Periodic","measurand":"Energy.Active.Import.Register","location":"Outlet","unit":"Wh"},{"value":" 0.0","context":"Sample.Periodic","measurand":"Power.Active.Import","location":"Outlet","unit":"W"},{"value":"230.0","context":"Sample.Periodic","measurand":"Voltage","phase":"L1-N","location":"Outlet","unit":"V"},{"value":"232.0","context":"Sample.Periodic","measurand":"Voltage","phase":"L2-N","location":"Outlet","unit":"V"},{"value":"229.0","context":"Sample.Periodic","measurand":"Voltage","phase":"L3-N","location":"Outlet","unit":"V"},{"value":"16.0","context":"Sample.Periodic","measurand":"Current.Import","phase":"L1","location":"Outlet","unit":"A"},{"value":"15.0","context":"Sample.Periodic","measurand":"Current.Import","phase":"L2","location":"Outlet","unit":"A"},{"value":"17.0","context":"Sample.Periodic","measurand":"Current.Import","phase":"L3","location":"Outlet","unit":"A"},{"value":"37.0","context":"Sample.Periodic","measurand":"Temperature","location":"Cable","unit":"Celsius"},{"value":"25.0","context":"Sample.Periodic","measurand":"SoC","location":"EV","unit