PLC Integration: WAGO PFC200 + CODESYS 3.5

Complete guide for configuring a WAGO PFC200 PLC to send PV and battery storage metrics to EnergyPal via HTTP POST.

Prerequisites

• Controller: WAGO PFC200 (750-8212) with e!RUNTIME
• CODESYS libraries: WagoAppHTTP, WagoTypes — install via Library Manager in CODESYS IDE
• Network: controller must have internet access (port 443/HTTPS). WAGO PFC200 includes built-in CA certificates.
• API key: your energy_connection_key from EnergyPal administrator
• Configured devices: device codes (e.g., PV-1, BESS-1) must be registered in EnergyPal. Verify with GET /v1/devices.

Step 1: Declare the Function Block FB_EnergyPalSender

Create a new POU of type FUNCTION_BLOCK in your CODESYS project. Paste the following variable declaration:

FUNCTION_BLOCK FB_EnergyPalSender
VAR_INPUT
    rSoC              : REAL;   (* Battery state of charge [%] *)
    rEnergyExported   : REAL;   (* BESS discharge meter [kWh] *)
    rEnergyImported   : REAL;   (* BESS charge meter [kWh] *)
    rPvGenerated1     : REAL;   (* PV-1 generation meter [kWh] *)
    rPvGenerated2     : REAL;   (* PV-2 generation meter [kWh] *)
    rEnergyConsumed   : REAL;   (* LOAD-0 consumption meter [kWh] *)
END_VAR
VAR_OUTPUT
    bBusy             : BOOL;   (* Request in progress *)
    bError            : BOOL;   (* Last request failed *)
    iHttpStatus       : INT;    (* HTTP response code *)
END_VAR
VAR
    fbHttpClient      : WagoAppHTTP.WagoHTTPClient;
    fbTimer           : TON;
    bSend             : BOOL;
    bRequestDone      : BOOL;
    sJson             : STRING(2048);
    sUrl              : STRING(255) := 'https://api.energypal.ai/v1/ingest';
    sApiKey           : STRING(255) := 'your-api-key';   (* <- insert your key *)
    sContentType      : STRING(64)  := 'application/json';
    sResponse         : STRING(1024);
END_VAR

Set sApiKey to your actual API key. Adjust device codes if different from PV-1, PV-2, BESS-1, LOAD-0.

Step 2: Implementation

In the implementation tab of FB_EnergyPalSender, paste the following code. The block builds a JSON payload with current metric values and sends it via HTTP POST every 15 minutes:

(* === Cyclic timer - send every 15 minutes === *)
fbTimer(IN := NOT fbTimer.Q, PT := T#900S);

IF fbTimer.Q AND NOT bBusy THEN
    bSend := TRUE;
END_IF

(* === Build JSON === *)
IF bSend THEN
    bSend  := FALSE;
    bBusy  := TRUE;
    bError := FALSE;

    sJson := CONCAT('{"metrics":{',
        '"PV-1":{"energy_generated_meter":', REAL_TO_STRING(rPvGenerated1), '},',
        '"PV-2":{"energy_generated_meter":', REAL_TO_STRING(rPvGenerated2), '},',
        '"BESS-1":{"soc":', REAL_TO_STRING(rSoC),
            ',"energy_exported_meter":', REAL_TO_STRING(rEnergyExported),
            ',"energy_imported_meter":', REAL_TO_STRING(rEnergyImported),
        '},',
        '"LOAD-0":{"energy_consumed_meter":', REAL_TO_STRING(rEnergyConsumed),
        '}}}');

    (* === Configure and send HTTP POST === *)
    fbHttpClient.sUrl         := sUrl;
    fbHttpClient.sContentType := sContentType;
    fbHttpClient.sRequestData := sJson;
    fbHttpClient.bExecute     := TRUE;

    (* Add X-API-Key header *)
    fbHttpClient.AddHeader('X-API-Key', sApiKey);
END_IF

(* === Handle response === *)
fbHttpClient();

IF fbHttpClient.bDone OR fbHttpClient.bError THEN
    bBusy       := FALSE;
    iHttpStatus := fbHttpClient.iStatusCode;
    bError      := fbHttpClient.bError OR (iHttpStatus <> 200);
    sResponse   := fbHttpClient.sResponseData;
    fbHttpClient.bExecute := FALSE;
END_IF

Step 3: Call from PLC_PRG

In your main program PLC_PRG, create an instance of the block and connect your process variables:

PROGRAM PLC_PRG
VAR
    fbSender : FB_EnergyPalSender;

    (* --- Insert your process variables here --- *)
    rSoC_BMS            : REAL;   (* e.g. Modbus read / analog input *)
    rExportMeter_BMS    : REAL;
    rImportMeter_BMS    : REAL;
    rPvMeter_Inverter1  : REAL;
    rPvMeter_Inverter2  : REAL;
    rConsumptionMeter   : REAL;   (* total energy consumed [kWh] *)
END_VAR

(* Call the sender block *)
fbSender(
    rSoC            := rSoC_BMS,
    rEnergyExported := rExportMeter_BMS,
    rEnergyImported := rImportMeter_BMS,
    rPvGenerated1   := rPvMeter_Inverter1,
    rPvGenerated2   := rPvMeter_Inverter2,
    rEnergyConsumed := rConsumptionMeter
);

(* Optional: diagnostics in visualization *)
(* fbSender.bBusy       - is sending in progress *)
(* fbSender.bError      - did the last send fail *)
(* fbSender.iHttpStatus - HTTP response code (200 = OK) *)

Configuration Notes

• Send interval: timer T#900S means sending every 15 minutes (matching system aggregation interval). Change to T#300S (5 minutes) for more redundancy in case of connection errors.
• Cumulative meters: energy_*_meter values must be always increasing. Never reset — the system calculates energy gain automatically.
• Error handling: if iHttpStatus is not 200, the block automatically retries on the next timer cycle. The system is idempotent — duplicates within a 15-minute window are skipped.
• Device codes: must exactly match the configuration in EnergyPal. Verify with GET /v1/devices.
• Custom devices: if you have a different number of inverters or batteries, adjust the sJson string building in the implementation.
• Diagnostics: output variables bBusy, bError, iHttpStatus can be connected to a CODESYS visualization to monitor sending status.

Reading Energy Prices

To fetch energy price forecasts on the WAGO PLC (for battery optimization), see the dedicated guide: Fetching Energy Prices (WAGO + CODESYS).

Testing with curl

Before configuring the PLC, test the API connection:

# Send test data
curl -X POST https://api.energypal.ai/v1/ingest \
  -H "Content-Type: application/json" \
  -H "X-API-Key: your-api-key" \
  -d '{
    "metrics": {
      "PV-1": {"energy_generated_meter": 12345.0},
      "BESS-1": {"soc": 85.5, "energy_exported_meter": 500.0, "energy_imported_meter": 450.0},
      "LOAD-0": {"energy_consumed_meter": 98765.0}
    }
  }'

# Verify your device codes
curl -H "X-API-Key: your-api-key" https://api.energypal.ai/v1/devices