wait for the end of read/write operations on the PLC

src/Actions/PLC.js

@@ -30,12 +30,14 @@ class PLC extends Action {
     this.cli = new NodeS7({ silent: true });
 
     this.run = cond([
-      /** @type {[function(PlcCmd): boolean, function(PlcCmd): void]} */
+      /** @type {[function(PlcCmd): boolean, function(PlcCmd): Promise<string>]} */
       ([ conforms({ 'address': isString, 'value': negate(isNil) }),
         this.write ]),
       [ conforms({ 'address': isString }), this.read ],
       [ () => true,
-        (cmd) => this.stderr(`Wrong PLC command [${cmd}].`) ]
+        (cmd) => {
+          throw new Error(`Wrong PLC command [${JSON.stringify(cmd)}].`);
+        } ]
     ]);
   }
 
@@ -58,7 +60,7 @@ class PLC extends Action {
     this.stdout(`Connecting to PLC... (host: '${this.host}'\n`);
     this._retProm = makeDeferred();
 
-    this.cli.initiateConnection(opts, (err) => {
+    this.cli.initiateConnection(opts, async (err) => {
       if (err) {
         // @ts-ignore: '_retProm' cannot be null here
         this._retProm.reject(new Error(
@@ -68,7 +70,11 @@ class PLC extends Action {
       }
       this.stdout(`Connected.\n`);
 
-      for (const cmd of plcCmds) { this.run(cmd); }
+      for (const cmd of plcCmds) {
+        await this.run(cmd)
+        .then(this.stdout)
+        .catch(this.stderr);
+      }
 
       this.cli.dropConnection(() => this.stdout('Disconnected.\n'));
 
@@ -81,48 +87,62 @@ class PLC extends Action {
 
   /**
    * @param {PlcCmd} cmd
+   * @return {Promise<string>}
    */
-  write(cmd) {
-    if (!this._retProm) { return; }
+  async write(cmd) {
+    if (!this._retProm) {
+      throw new Error(`Cannot execute command '${JSON.stringify(cmd)}'`);
+    }
+    const done = makeDeferred();
 
     const code = this.cli.writeItems(cmd.address,
       /** @type {NodeS7.S7Types} */(cmd.value), (err) => {
         if (err) {
-          this.stderr(`Failed to perform command '${JSON.stringify(cmd)}': ` +
-            'invalid command.');
+          done.reject(
+            new Error(`Failed to perform command '${JSON.stringify(cmd)}': ` +
+            'invalid command.'));
         }
         else {
-          this.stdout(`Command '${JSON.stringify(cmd)}' done.`);
+          done.resolve(`Command '${JSON.stringify(cmd)}' done.`);
         }
       });
 
     if (code !== 0) {
-      this.stderr(`Failed to perform command '${JSON.stringify(cmd)}': ` +
-        'another writing is in progress.');
+      done.reject(
+        new Error(`Failed to perform command '${JSON.stringify(cmd)}': ` +
+        'another writing is in progress.'));
     }
+    return done.promise;
   }
 
   /**
    * @param {PlcCmd} cmd
+   * @return {Promise<string>}
    */
-  read(cmd) {
-    if (!this._retProm) { return; }
+  async read(cmd) {
+    if (!this._retProm) {
+      throw new Error(`Cannot execute command '${JSON.stringify(cmd)}'`);
+    }
+    const done = makeDeferred();
 
     this.cli.addItems(cmd.address);
     this.cli.readAllItems((err, values) => {
       if (err) {
-        this.stderr(`Failed to perform command '${JSON.stringify(cmd)}': ` +
-          'invalid command.\n');
+        done.reject(
+          new Error(`Failed to perform command '${JSON.stringify(cmd)}': ` +
+          'invalid command.\n'));
       }
       else if (values) {
-        this.stdout('Values read:\n');
-        forOwn(values, (val, key) => this.stdout(`${key}: ${val}\n`));
+        let output = 'Values read:\n';
+        forOwn(values, (val, key) => { output += `- '${key}': ${val}\n`; });
+        done.resolve(output);
       }
       else {
-        this.stderr(
-          `Command '${JSON.stringify(cmd)}' performed but no value read.\n`);
+        done.reject(new Error(
+          `Command '${JSON.stringify(cmd)}' performed but no value read.\n`));
       }
     });
+    return done.promise;
   }
 }