From 80a471a039c0d7cec27c8b9da016dc0e09be9d62 Mon Sep 17 00:00:00 2001
From: Dom Bernero <dbernero@gridpoint.com>
Date: Thu, 16 Oct 2025 15:11:08 -0400
Subject: [PATCH 1/2] Add function to expose TCP connection status

---
 lib/tcp/client.ex | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/lib/tcp/client.ex b/lib/tcp/client.ex
index 977479f..e5121cb 100644
--- a/lib/tcp/client.ex
+++ b/lib/tcp/client.ex
@@ -130,6 +130,13 @@ defmodule Modbux.Tcp.Client do
     GenServer.call(pid, :flush)
   end
 
+  @doc """
+  Determine if the Client is connected to a Server.
+  """
+  def connected?(pid) do
+    GenServer.call(pid, :connected?)
+  end
+
   # callbacks
   def init(args) do
     port = args[:tcp_port] || @port
@@ -311,6 +318,11 @@ defmodule Modbux.Tcp.Client do
     {:reply, {:ok, state.pending_msg}, new_state}
   end
 
+  def handle_call(:connected?, _from, state) do
+    connected? = state.socket != nil && state.status == :connected
+    {:reply, connected?, state}
+  end
+
   # only for active mode (active: true)
   def handle_info({:tcp, _port, response}, state) do
     Logger.debug("(#{__MODULE__}, :message_active) response: #{inspect(response)}")

From 5e2abe5fd2ba91c781799c0ceb92cde99ee1a226 Mon Sep 17 00:00:00 2001
From: Dom Bernero <dbernero@gridpoint.com>
Date: Thu, 16 Oct 2025 15:11:24 -0400
Subject: [PATCH 2/2] Add Tcp.Client.connected?/1 unit test

---
 test/tcp/modbus_tcp_client_test.exs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/test/tcp/modbus_tcp_client_test.exs b/test/tcp/modbus_tcp_client_test.exs
index fba0ed7..f862e8b 100644
--- a/test/tcp/modbus_tcp_client_test.exs
+++ b/test/tcp/modbus_tcp_client_test.exs
@@ -19,4 +19,15 @@ defmodule ModbuxTcpClientTest do
     assert {:error, :econnrefused} == Client.connect(cpid)
     assert {:error, :closed} == Client.close(cpid)
   end
+
+  test "test Client connectivity status" do
+    {:ok, _spid} = Server.start_link(model: %{}, port: 2000)
+    {:ok, cpid} = Client.start_link(ip: {127, 0, 0, 1}, tcp_port: 2000)
+    assert false == Client.connected?(cpid)
+    assert :ok == Client.connect(cpid)
+    assert true == Client.connected?(cpid)
+    assert :ok == Client.close(cpid)
+    assert false == Client.connected?(cpid)
+    assert :ok == Client.stop(cpid)
+  end
 end