Add very basic Modbus sensor support

Closes #55

package.json

@@ -33,6 +33,7 @@
   "dependencies": {
     "@influxdata/influxdb-client": "^1.33.2",
     "axios": "^1.6.0",
+    "modbus-serial": "^8.0.16",
     "mqtt": "^5.1.2",
     "slugify": "^1.6.6",
     "winston": "^3.11.0",

src/config.ts

@@ -7,6 +7,7 @@ import {
   getCharacteristicsSensorData as getIotawattCharacteristicsSensorData,
   getSensorData as getIotawattSensorData,
 } from './sensor/iotawatt'
+import { getSensorData as getModbusSensorData } from './sensor/modbus'
 import { getSensorData as getVirtualSensorData } from './sensor/virtual'
 import { getSensorData as getUnmeteredSensorData } from './sensor/unmetered'
 import {
@@ -153,6 +154,9 @@ export const resolveAndValidateConfig = (config: Config): Config => {
       case SensorType.Iotawatt:
         circuit.sensor.pollFunc = getIotawattSensorData
         break
+      case SensorType.Modbus:
+        circuit.sensor.pollFunc = getModbusSensorData
+        break
       case SensorType.Virtual:
         circuit.sensor.pollFunc = getVirtualSensorData
         break

src/eachwatt.ts

@@ -9,7 +9,8 @@ import { WebSocketPublisherImpl } from './publisher/websocket'
 import { PublisherType } from './publisher'
 import { pollCharacteristicsSensors } from './characteristics'
 import { createLogger } from './logger'
-import { setRequestTimeout } from './http/client'
+import { setRequestTimeout as setHttpRequestTimeout } from './http/client'
+import { setRequestTimeout as setModbusRequestTimeout } from './modbus/client'
 
 // Set up a signal handler, so we can exit on Ctrl + C when run from Docker
 process.on('SIGINT', () => {
@@ -101,10 +102,12 @@ const mainPollerFunc = async (config: Config) => {
     publisherImpl: webSocketServer,
   })
 
-  // Adjust the HTTP timeout to be half that of the polling interval
+  // Adjust request timeouts to be half that of the polling interval
   const pollingInterval = config.settings.pollingInterval
   logger.info(`Polling sensors with interval ${pollingInterval} milliseconds`)
-  setRequestTimeout((pollingInterval as number) / 2)
+  const timeoutMs = (pollingInterval as number) / 2
+  setHttpRequestTimeout(timeoutMs)
+  setModbusRequestTimeout(timeoutMs)
 
   // Start polling sensors
   await mainPollerFunc(config)

src/modbus/client.ts

@@ -0,0 +1,24 @@
+import { createLogger } from '../logger'
+import ModbusRTU from 'modbus-serial'
+
+const logger = createLogger('modbus')
+
+// Request timeout configuration
+export let requestTimeout = 5000
+
+export const setRequestTimeout = (timeoutMs: number) => {
+  requestTimeout = timeoutMs
+  logger.info(`Using ${timeoutMs} millisecond timeout for Modbus operations`)
+}
+
+// Keep track of clients, use one per address
+const clients = new Map<string, ModbusRTU>()
+
+export const getClient = (address: string): ModbusRTU => {
+  if (!clients.has(address)) {
+    const client = new ModbusRTU()
+    clients.set(address, client)
+  }
+
+  return clients.get(address) as ModbusRTU
+}

src/sensor.ts

@@ -4,6 +4,7 @@ import { Characteristics } from './characteristics'
 export enum SensorType {
   Iotawatt = 'iotawatt',
   Shelly = 'shelly',
+  Modbus = 'modbus',
   Virtual = 'virtual',
   Unmetered = 'unmetered',
   Dummy = 'dummy',
@@ -76,6 +77,19 @@ export interface IotawattSensor extends PowerSensor {
   iotawatt: IotawattSensorSettings
 }
 
+export interface ModbusSensorSettings {
+  address: string
+  port: number
+  unit: number
+  register: number
+  type: 'int16'
+}
+
+export interface ModbusSensor extends PowerSensor {
+  type: SensorType.Modbus
+  modbus: ModbusSensorSettings
+}
+
 interface VirtualSensorSettings {
   children: (string | Circuit)[] // resolved to circuit at runtime
 }