From 7db569872c1684a33e9f251b04097f170e96baaa Mon Sep 17 00:00:00 2001
From: Graziano Grespan <graziano.grespan@emerson.com>
Date: Fri, 16 Aug 2024 19:56:15 +0200
Subject: [PATCH] feat: Allow close method to be used with Promises or
 callbacks

---
 index.js | 29 ++++++++++++++++++++---------
 1 file changed, 20 insertions(+), 9 deletions(-)

diff --git a/index.js b/index.js
index 04242ac..26ac6e1 100644
--- a/index.js
+++ b/index.js
@@ -669,16 +669,27 @@ class ModbusRTU extends EventEmitter {
      *
      * @param {Function} callback the function to call next on close success
      *      or failure.
-     */
+     */    
     close(callback) {
-        // close the serial port if exist
-        if (this._port) {
-            this._port.removeAllListeners("data");
-            this._port.close(callback);
-        } else {
-            // nothing needed to be done
-            callback();
-        }
+        return new Promise((resolve, reject) => {
+            const cb = (err) => {
+                if (callback) {
+                    callback(err);
+                }
+                if (err) {
+                    reject(err);
+                } else {
+                    resolve();
+                }
+            };
+    
+            if (this._port) {
+                this._port.removeAllListeners("data");
+                this._port.close(cb);
+            } else {
+                cb();
+            }
+        });
     }
 
     /**