diff --git a/modbus/modbus_tools/modbusConnect.ini b/modbus/modbus_tools/modbusConnect.ini
index 83f0dcc..0976d43 100644
--- a/modbus/modbus_tools/modbusConnect.ini
+++ b/modbus/modbus_tools/modbusConnect.ini
@@ -1,5 +1,5 @@
 [MODBUS_SLAVE]
-SLAVE_IP_ADDR=192.168.50.155
+SLAVE_IP_ADDR=192.168.1.16
 SLAVE_IP_PORT=502
 
 
diff --git a/modbus/modbus_tools/ysp_modbus_master.cpp b/modbus/modbus_tools/ysp_modbus_master.cpp
index 9df7994..0b38609 100644
--- a/modbus/modbus_tools/ysp_modbus_master.cpp
+++ b/modbus/modbus_tools/ysp_modbus_master.cpp
@@ -92,19 +92,27 @@ DWORD WINAPI xModbus_master_Proc(LPVOID lp) {
 	}
 
 	modbus_set_response_timeout(ctx, 20, 0);
-	sockt = modbus_connect(ctx);
-	if (sockt == -1) {
-		fprintf(stderr, "Connection failed: %s\n", modbus_strerror(errno));
-		modbus_free(ctx);
-		return -1;
-	}
+	while (1) {
+		if (sockt <= 0)
+		{
+			sockt = modbus_connect(ctx);
+			if (sockt == -1) {
+				fprintf(stderr, "Connection failed: %s\n", modbus_strerror(errno));
+				//modbus_free(ctx);
+				Sleep(1);
+				continue;
+			}
+			else
+			{
+				printf("Connection Success! socket=%d\n", sockt);
+			}
+		}
 
-	unsigned char* src = (unsigned char*)tab_rp_registers;
-	while (1)
-	{
-#if 0
-		if (sockt < 0)
-			return -1;
+		unsigned char* src = (unsigned char*)tab_rp_registers;
+
+#if 1
+		if (sockt <= 0)
+			continue;
 		FD_ZERO(&fdset_ro);
 		FD_ZERO(&fdset_wr);
 		FD_ZERO(&fdset_ex);
@@ -124,18 +132,25 @@ DWORD WINAPI xModbus_master_Proc(LPVOID lp) {
 			sockt = -1;
 			break;
 		}
-		if (FD_ISSET(sockt, &fdset_ro))
+		if (FD_ISSET(sockt, &fdset_wr)) {
+#endif
+			rc = modbus_read_registers(ctx, start_hold_register, number_regs, tab_rp_registers);
+#if 1
+			if (rc == -1)
+			{
+				closesocket(sockt);
+				sockt = -1;
+				printf("End ThreadŁĄ\n");
+				continue;
+			}
 #endif
-		rc = modbus_read_registers(ctx, start_hold_register, number_regs, tab_rp_registers);
-#if 0
-		if (rc == -1)
+		}
+		else
 		{
-			closesocket(sockt);
-			sockt = -1;
-			printf("End ThreadŁĄ\n");
-			return -1;
+			Sleep(1000);
+			continue;
 		}
-#endif
+
 		Sleep(3 * 1000);
 		//xUnsigned_char_hex_out("recv", src, 0, number_regs*2);
 		xRead_reg_hex_out(start_hold_register, "master recv", src, 0, number_regs * 2);