// ============================================================
//  SIGEN RS485 MONITOR -- Shelly device with Modbus RS485 addon
//
//  Reads live Sigenergy solar data directly from the gateway
//  via Modbus RS485 -- fully local, no internet, no laptop.
//
//  Prerequisites:
//    1. Shelly Modbus RS485 addon physically wired to the
//       Sigenergy gateway RS485 port (A+ -> A+, B- -> B-, GND -> GND)
//    2. RS485 addon configured in Shelly Web UI:
//         Settings -> Addon -> RS485
//         Baud rate, parity, stop bits: match gateway spec sheet
//         (typically 9600 or 19200 baud, 8N1 or 8E1)
//    3. Five Virtual Components (number type) created on this device:
//         VC 200 PV Power (W)       VC 203 Grid Power (W)
//         VC 201 Battery SOC (%)    VC 204 Load Power (W)
//         VC 202 Battery Power (W)
//
//  Modbus register map (input registers, FC04, Unit ID 247):
//    Signal       Register  PDU addr  Count  Type    Scale
//    gridPower    30005      4        2      int32   1 W    (+import / -export)
//    batterySoc   30014     13        1      uint16  0.1 %
//    pvPower      30035     34        2      int32   1 W
//    batteryPower 30037     36        2      int32   1 W    (+charging)
//    loadPower    30284    283        2      int32   1 W
//
//  PDU address = register number - 30001  (0-indexed for FC04)
// ============================================================

var UNIT_ID  = 247;
var POLL_MS  = 30000;  // poll every 30 seconds

// VC IDs
var VC_PV   = 200;
var VC_SOC  = 201;
var VC_BAT  = 202;
var VC_GRID = 203;
var VC_LOAD = 204;

// Collected values (filled sequentially, pushed to VCs when all ready)
var vals = {};

// Convert two uint16 Modbus registers to a signed int32
function to_int32(hi, lo) {
  var u = hi * 65536 + lo;
  if (u > 2147483647) u = u - 4294967296;
  return u;
}

function setVC(id, value) {
  Virtual.getHandle("number:" + id).setValue(value);
}

// ── Step 5: write all values to VCs ──────────────────────────────────────────
function pushToVCs() {
  setVC(VC_PV,   vals.pvW);
  setVC(VC_SOC,  vals.socPc);
  setVC(VC_BAT,  vals.batW);
  setVC(VC_GRID, vals.griW);
  setVC(VC_LOAD, vals.loadW);
  print("[rs485] PV=" + vals.pvW + "W SOC=" + vals.socPc +
        "% Bat=" + vals.batW + "W Grid=" + vals.griW +
        "W Load=" + vals.loadW + "W");
}

// ── Step 4: read loadPower (30284, addr 283, 2 regs, int32) ──────────────────
function readLoad() {
  Shelly.call("Modbus.Read", {
    device_id: UNIT_ID,
    type: "input_registers",
    addr: 283,
    count: 2
  }, function(res, err) {
    if (err !== 0 || !res) { print("[rs485] err readLoad:", err); return; }
    vals.loadW = to_int32(res.values[0], res.values[1]);
    pushToVCs();
  });
}

// ── Step 3: read batteryPower (30037, addr 36, 2 regs, int32) ────────────────
function readBatteryPower() {
  Shelly.call("Modbus.Read", {
    device_id: UNIT_ID,
    type: "input_registers",
    addr: 36,
    count: 2
  }, function(res, err) {
    if (err !== 0 || !res) { print("[rs485] err readBatteryPower:", err); return; }
    vals.batW = to_int32(res.values[0], res.values[1]);
    readLoad();
  });
}

// ── Step 2b: read pvPower (30035, addr 34, 2 regs, int32) ────────────────────
function readPV() {
  Shelly.call("Modbus.Read", {
    device_id: UNIT_ID,
    type: "input_registers",
    addr: 34,
    count: 2
  }, function(res, err) {
    if (err !== 0 || !res) { print("[rs485] err readPV:", err); return; }
    vals.pvW = to_int32(res.values[0], res.values[1]);
    readBatteryPower();
  });
}

// ── Step 2a: read batterySoc (30014, addr 13, 1 reg, uint16 x0.1) ────────────
function readSOC() {
  Shelly.call("Modbus.Read", {
    device_id: UNIT_ID,
    type: "input_registers",
    addr: 13,
    count: 1
  }, function(res, err) {
    if (err !== 0 || !res) { print("[rs485] err readSOC:", err); return; }
    vals.socPc = res.values[0] * 0.1;
    readPV();
  });
}

// ── Step 1: read gridPower (30005, addr 4, 2 regs, int32) ────────────────────
// Grid sign: Modbus + = import from grid, VC 203 + = export -> negate
function readGrid() {
  Shelly.call("Modbus.Read", {
    device_id: UNIT_ID,
    type: "input_registers",
    addr: 4,
    count: 2
  }, function(res, err) {
    if (err !== 0 || !res) { print("[rs485] err readGrid:", err); return; }
    vals.griW = -to_int32(res.values[0], res.values[1]);  // negate for VC sign
    readSOC();
  });
}

// ── Poll loop ─────────────────────────────────────────────────────────────────
function poll() {
  vals = {};
  readGrid();
}

Timer.set(POLL_MS, true, poll, null);
poll();
print("Sigen RS485 monitor started, polling every", POLL_MS / 1000, "s");