From 05b9b3b5783b1d89f23ef1231adb642467de7641 Mon Sep 17 00:00:00 2001
From: jan iversen <jancasacondor@gmail.com>
Date: Thu, 20 Jul 2023 19:58:58 +0200
Subject: [PATCH] Check if serial is installed.

---
 pymodbus/transport/serial_asyncio/__init__.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/pymodbus/transport/serial_asyncio/__init__.py b/pymodbus/transport/serial_asyncio/__init__.py
index a52ef7b284..e9858d9c4d 100644
--- a/pymodbus/transport/serial_asyncio/__init__.py
+++ b/pymodbus/transport/serial_asyncio/__init__.py
@@ -19,9 +19,10 @@
 import os
 
 
-with contextlib.suppress(ImportError):
+try:
     import serial
-
+except ImportError:
+    serial = None
 
 try:
     import termios
@@ -48,6 +49,9 @@ class SerialTransport(asyncio.Transport):
     """
 
     def __init__(self, loop, protocol, serial_instance):
+        assert (
+            not serial
+        ), '***ERROR*** "serial" not installed, needed to run modbus serial communication'
         super().__init__()
         self._loop = loop
         self._protocol = protocol