---
title: "WIZ750SR TCP Server mode Port closed"
url: "https://maker.wiznet.io/forum/13316"
markdown_url: "https://maker.wiznet.io/forum/13316/md"
type: "Forum topic"
category: "Serial-to-Ethernet & ConfigTool"
author: "moritz"
created: "2019-05-10T14:50:48+09:00"
last_activity: "2019-07-02T04:07:08+09:00"
language: "en"
views: 964
replies: 2
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# WIZ750SR TCP Server mode Port closed

## Question

Asked by moritz on 2019-05-10 in Serial-to-Ethernet & ConfigTool.

I am running the WIZ750SR in TCP Server mode and when I try to connect to it I get “Connection refused”. I scanned the device for open ports and only the port (50001) for Settings seems to be open, port 5000 is closed.

The weird thing is that the setup was already running like this before but now it does not work anymore. I have no clue as to what changed.

Here are my settings from the debug terminal:

```
==================================================
 WIZ750SR 
 >> WIZnet Serial to Ethernet Device
 >> Firmware version: 1.2.4 Stable
==================================================
 - Device name: WIZ750SR
 - Device mode: TCP_SERVER_MODE
 - Network settings: 
	- Obtaining IP settings: [Static]
	- TCP/UDP ports
	   + S2E data port: [5000]
	   + TCP/UDP setting port: [50001]
	   + Firmware update port: [50002]
	- TCP Retransmission retry: [8]
 - Search ID code: 
	- Disabled: [None]
 - Ethernet connection password: 
	- Disabled (TCP server / mixed mode only)
 - Connection timer settings: 
	- Inactivity timer: Disabled
	- Reconnect interval: [3000] (msec)
 - Serial settings: 
	- Data UART port:  [UART0]
	   + UART IF: [RS-232/TTL]
	   + 115200-8-N-1 / Flow control: NONE
	- Debug UART port: [UART2]
	   + 115200-8-N-1 / NONE (fixed)
 - Serial data packing options:
	- Time: Disabled
	- Size: Disabled
	- Char: Disabled
 - Serial command mode switch code:
	- Enabled
	- [2B][2B][2B] (Hex only)
 - Hardware information: Status pins
	- Status 1: [PA_10] - PHY link
	- Status 2: [PA_01] - TCP connection
 - Hardware information: User I/O pins
	- UserIO A: [PC_13] - Digital / Input
	- UserIO B: [PC_12] - Digital / Input
	- UserIO C: [PC_09] - Digital / Input
	- UserIO D: [PC_08] - Digital / Input
==================================================
 # MAC: 00:08:DC:54:8A:6F
 # IP : 192.168.30.48 / Port: 5000
 # GW : 192.168.30.1
 # SN : 255.255.254.0
 # DNS: 8.8.8.8

 SEG:AT Mode
```

And when scanning the ports with nmap this is the result:

> ```
Starting Nmap 7.01 ( https://nmap.org ) at 2019-05-10 16:49 CEST
Nmap scan report for 192.168.30.48
Host is up (0.00013s latency).
Not shown: 999 closed ports
PORT      STATE SERVICE
50001/tcp open  unknown
MAC Address: 00:08:DC:54:8A:6F (Wiznet)

Nmap done: 1 IP address (1 host up) scanned in 1.62 seconds
```

Any ideas what could be wrong here?

## Replies

### Reply 1 by moritz, 2019-06-19

Anyone?

### Reply 2 by rena, 2019-07-02

Hello [@moritz](https://maker.wiznet.io/u/moritz)
Sorry for the late reply.

![](https://avatars.discourse-cdn.com/v4/letter/m/58956e/48.png) moritz:

> SEG:AT Mode

When the module is serial command mode (AT mode), TCP communication is not available.

In debug message, the device’s state is AT mode.
Please refer to the wiki page below to change the mode.

- [Entering Serial Command Mode](http://wizwiki.net/wiki/doku.php?id=products:wiz750sr:commandmanual:en#entering_serial_command_mode)

Note that in the TCP server mode, the log is output as follows.

```
==================================================
 WIZ750SR
 >> WIZnet Serial to Ethernet Device
 >> Firmware version: 1.2.4 Stable
==================================================
 - Device name: WIZ750SR
 - Device mode: TCP_SERVER_MODE
 - Network settings:
        - Obtaining IP settings: [Static]
        - TCP/UDP ports
           + S2E data port: [5000]
           + TCP/UDP setting port: [50001]
           + Firmware update port: [50002]
        - TCP Retransmission retry: [8]
 - Search ID code:
        - Disabled: [None]
 - Ethernet connection password:
        - Disabled (TCP server / mixed mode only)
 - Connection timer settings:
        - Inactivity timer: Disabled
        - Reconnect interval: [3000] (msec)
 - Serial settings:
        - Data UART port:  [UART0]
           + UART IF: [RS-232/TTL]
           + 230400-8-N-1 / Flow control: NONE
        - Debug UART port: [UART2]
           + 115200-8-N-1 / NONE (fixed)
 - Serial data packing options:
        - Time: Disabled
        - Size: Disabled
        - Char: Disabled
 - Serial command mode switch code:
        - Enabled
        - [2B][2B][2B] (Hex only)
 - Hardware information: Status pins
        - Status 1: [PA_10] - PHY link
        - Status 2: [PA_01] - TCP connection
 - Hardware information: User I/O pins
        - UserIO A: [PC_13] - Analog / Input
        - UserIO B: [PC_12] - Digital / Input
        - UserIO C: [PC_09] - Digital / Output
        - UserIO D: [PC_08] - Digital / Output
==================================================
 # MAC: 00:08:DC:53:AE:21
 # IP : 192.168.50.100 / Port: 5000
 # GW : 192.168.50.1
 # SN : 255.255.255.0
 # DNS: 8.8.8.8

 > SEG:TCP_SERVER_MODE:SOCKOPEN
```

Thank you.

---

Source: https://maker.wiznet.io/forum/13316