unified modbus readings into a single mqtt payload (#30)

Instathings · Aug 25, 2022 · f2b35bb · f2b35bb
1 parent a5cbc67
commit f2b35bb
Showing 1 changed file with 44 additions and 29 deletions.
diff --git a/lib/modbus.js b/lib/modbus.js
@@ -7,6 +7,8 @@ const { default: ModbusRTU } = require('modbus-serial');
 const delay = ms => new Promise(r => setTimeout(r, ms));
 
 class Modbus extends events.EventEmitter {
+  supportedFCs = [3, 4];
+
   constructor(mqtt, modbus, device) {
     super();
     this.mqtt = mqtt;
@@ -41,38 +43,52 @@ class Modbus extends events.EventEmitter {
 
   /**
    * the modbus function code. now supports only 3 and 4. default is 4
-   * @param {number} functionCode default is 4
+   * @param {number[]} functionCodes default is [3, 4]
    */
-  async pollRegistersByFC(functionCode = 4) {
-    if (!functionCode) throw Error('function code must be provided for polling');
-    if (functionCode !== 3 && functionCode !== 4) throw Error('only FC3 and FC4 are supported for polling');
-    const descriptorRegistersProperty = functionCode === 4 ? 'input' : 'keep';
+  async pollRegisters(functionCodes = this.supportedFCs) {
+    if (!functionCodes) throw Error('function code must be provided for polling');
     await this.modbus.setID(this.modbusId);
     const result = {};
-    const input = _.get(this.descriptor, `fromModbus.${descriptorRegistersProperty}`);
-    const keys = Object.keys(input);
-    // eslint-disable-next-line
-    for (let key of keys) {
-      const addressDescriptor = _.get(input, key);
-      const address = _.get(addressDescriptor, 'address');
-      let value;
-      try {
-        const promise = functionCode === 4
-          ? this.modbus.readInputRegisters.bind(this.modbus)
-          : this.modbus.readHoldingRegisters.bind(this.modbus);
-        // eslint-disable-next-line no-await-in-loop
-        value = await promise(address, 1);
-        // eslint-disable-next-line no-await-in-loop
-        await delay(300);
-      } catch (err) {
-        logger.error(err);
+    for (const fc of functionCodes) {
+      const descriptorRegistersProperty = fc === 4 ? 'input' : 'keep';
+      const input = _.get(this.descriptor, `fromModbus.${descriptorRegistersProperty}`);
+      const keys = Object.keys(input);
+      console.log(`reading with FC${fc}`);
+      if (!this.supportedFCs.includes(fc)) {
+        console.error(`FC${fc} not supported. skipping to next FC...`);
+        continue;
+      }
+      let promise;
+      if (fc === 3) {
+        promise = this.modbus.readHoldingRegisters.bind(this.modbus)
+      } else if (fc === 4) {
+        promise = this.modbus.readInputRegisters.bind(this.modbus)
+      } else {
+        console.error(`FC${fc} not supported. skipping to next FC...`);
+        continue;
+      }
+      // eslint-disable-next-line
+      for (let key of keys) {
+        const addressDescriptor = _.get(input, key);
+        const address = _.get(addressDescriptor, 'address');
+        let value;
+        const registersCountToRead = _.get(addressDescriptor, 'count') || 1;
+        try {
+          // eslint-disable-next-line no-await-in-loop
+          value = await promise(address, registersCountToRead);
+          // eslint-disable-next-line no-await-in-loop
+          await delay(300);
+          const { post } = addressDescriptor;
+          const interpreted = registersCountToRead === 1 ? _.get(value, 'data[0]') : value.data;
+          const raw = _.get(value, 'buffer');
+          value = (post) ? post(interpreted, raw) : interpreted;
+          _.set(result, key, value);
+        } catch (err) {
+          logger.error(err);
+        }
       }
-      const { post } = addressDescriptor;
-      const interpreted = _.get(value, 'data[0]');
-      const raw = _.get(value, 'buffer');
-      value = (post) ? post(interpreted, raw) : interpreted;
-      _.set(result, key, value);
     }
+
     const topic = `${this.id}`;
     const payload = JSON.stringify(result);
     this.mqtt.publish(topic, payload);
@@ -82,8 +98,7 @@ class Modbus extends events.EventEmitter {
     try {
       await this.modbus.setID(this.modbusId);
       // error handling is done within the invoked function so we can call both polls sequentially
-      await this.pollRegistersByFC(3);
-      await this.pollRegistersByFC(4);
+      await this.pollRegisters();
     } catch (err) {
       logger.error(err);
     }