---
title: "WIZ750SR and DHCP enabled"
url: "https://maker.wiznet.io/forum/13602"
markdown_url: "https://maker.wiznet.io/forum/13602/md"
type: "Forum topic"
category: "Serial-to-Ethernet & ConfigTool"
author: "Nagarajan V"
created: "2019-12-10T06:32:10+09:00"
last_activity: "2020-03-25T13:50:35+09:00"
language: "en"
views: 1807
replies: 31
source: "WIZnet Makers forum (https://maker.wiznet.io/forum/)"
---

# WIZ750SR and DHCP enabled

## Question

Asked by Nagarajan V on 2019-12-10 in Serial-to-Ethernet & ConfigTool.

Wiz750SR with DCHP enabled condition, the connection is breaking more offen.
So data transfer is not completed.

Without DHCP, data transfer is working fine.

Firmware version is 1.2.4
Anybody have this issue?

V.Nagarajan

## Replies

### Reply 1 by becky, 2019-12-10

I’ll give it a try as your condition in our side and let you know the result.
Please wait some time~

### Reply 2 by Nagarajan V, 2019-12-11

Dear becky

There is wrong data conversion after starting data transfer randomly.
Actual data sent on RS232 side is 66 03 00 00 97 ff but on ethernet side with wireshark is 02 01 06 00 81 4a when DHCP is enabled.

V.Nagarajan

### Reply 3 by Nagarajan V, 2019-12-18

Dear Becky

Any feedback for the problem mentioned?

V.Nagarajan

### Reply 4 by becky, 2019-12-19 (in reply to reply 3)

Sorry I’m late
I tested it, but it worked.
![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/7/71d8ce1eca1fd12eb9781fdfe818c4f620c42ab6.png)
![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/4/4f1ae07a1aed597036652ae4b0d34b8183d6b71c.png)
![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/2/2991032455e34644862e288e6f1cb67b13464f00.png)

So I want to know your network environment or other information.
I also think that if you update the firmware to version 1.2.9 it might be helpful.

### Reply 5 by Nagarajan V, 2019-12-19

Thank you for the feedback
I have updated the firmware to 1.2.9. The problem persists.

Please find wireshark capture and config snapshot.
Use dispaly filter in wireshark as “tcp.port==4321” without quotes for viewing tcp transfers.

[Wiz DHCP problem.rar - FileTransfer.io](https://filetransfer.io/data-package/nbE169Hu)

Please note before closing tcp connection last received data is wrong.

actual data is 66 01 00 02 97 ff
wrong data is 02 01 00 02 97 ff

If i disable DHCP, there is no issue with other settings kept same.

Kindly check and give feedback.

Thank you for your time.

V.Nagarajan

### Reply 6 by Nagarajan V, 2019-12-26

Dear Becky

Any feedback for the input provided?

V.Nagarajan

### Reply 7 by Nagarajan V, 2019-12-27

Dear Bong
I have tested more than one module. The problem repeats with all modules.
I think there is some issue when DHCP is enabled. It randomly corrupts one or two bytes of data.

We can demostrate the problem with team viewer if possible for you check.

V.Nagarajan

### Reply 8 by Nagarajan V, 2019-12-28

Dear Bong

Thank you for your attention. Regarding testing at my side, i would to like point out that i am using protocol as below:

[PC Software] SOT packet 6 bytes (11 01 00 00 ee ff) ----------->
<----------- [Wiz Serial Device]ACK packet 6 bytes (66 01 00 02 97 ff)
[PC Software] CMD packet 9 bytes (33 02 01 00 ca ff 14 ec ff) ---------->
<----------- [Wiz Serial Device] ACK packet 6 bytes (66 02 00 00 98 ff)
[PC Software] DATA packet 285 bytes (22 03 15 01 c5 ff …) ---------->
<----------- [Wiz Serial Device] ACK packet 6 bytes (66 03 00 00 97 ff)

Above sequence repeats until all product(1000) is updated to embedded system.
Totally 6000 packets sent and received for 1000 products.

I am facing problem in this condition. For timing and actual data kindly refer wireshark .pcap file given earlier.

Thanks for your time.

V.Nagarajan

### Reply 9 by becky, 2020-01-02 (in reply to reply 8)

![](https://avatars.discourse-cdn.com/v4/letter/b/e9bcb4/48.png) Bong:

> So, with the result, Becky will post again.

I tested it for 2day.
But we don’t see data broken.
We have difficult to debug because can’t reenact your situation.
So I want to know your serial program, data transfer period time and data.

Also, I imaged your situation as you said.

[![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/8/8201ca8d7570754040bb118d5e4585a2da671ee8.png) image1681×997 329 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/8/8201ca8d7570754040bb118d5e4585a2da671ee8.png)

There are problem in situation 3 or situation 4.
I think the use of dhcp does not affect data communication.
So could you please check the situation 3 as bong said.

![](https://avatars.discourse-cdn.com/v4/letter/b/e9bcb4/48.png) Bong:

> I think, if you possible, could you please test it with another serial device such as PC terminal as Becky did?

Alternatively, please check the data sent by the serial device.
I attach firmware which can check serial data from WIZ750SR to Debugging port.
This firmware recvs serial data and sends it to the debugging port before sending it to ethernet.
[W7500x_S2E_App.bin](https://maker.wiznet.io/forum/legacyFile.asp?path=2g9Xl2MGvzCxrgg7isJC7PbJJEG.bin) (38.8 KB)

You said 1000 products are updated.
Do you have a problem with only one product?
If you possible, could you please check it.

Nagarajan_V:

> Totally 6000 packets sent and received for 1000 products.

And I wonder you DHCP server.
please say me your DHCP server information and setting such as leasetime.

### Reply 10 by Nagarajan V, 2020-01-02

Dear Becky

Please find my testing logs.

[LOG.zip](https://maker.wiznet.io/forum/legacyFile.asp?path=9mGlRYcGdsawux7nkqkKsVeHRWD.zip) (3.9 KB)
Please note with DHCP Enabled condition, data broke at 79 and 48. See the last data in each is wrongly received. Failure happens randomly.
Without DHCP, all 423 product sent successfully.

Please see below image for failure condition:

[![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/5/521e6a5953b14bc7d27f7dd93416ed1660a2dcf1.png) image1360×744 48.3 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/5/521e6a5953b14bc7d27f7dd93416ed1660a2dcf1.png)

Please see below image for pass condition:

[![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/c/c724504a0b1ca4d5dde252faeceeb3d734be920a.png) image1360×742 48.3 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/c/c724504a0b1ca4d5dde252faeceeb3d734be920a.png)

For your information, we are sure that our sending data is correct(double checked using hardware monitor). It seems, data receiving problem in Wiz750 when DHCP is enabled.

With lower baud rate 9600 also, this problem happens.
When DHCP is enabled, data is breaking.

Waiting for your reply.

V.Nagarajan

### Reply 11 by becky, 2020-01-08

So we will test with baud 4800 and enable DHCP and find out exact reason of the problem
And let you know asap.
we are afraid that can’t immediately find out exact reason in the source code.

### Reply 12 by irina, 2020-01-08

Nagarajan_V:

> With lower baud rate 9600 also, this problem happens.
> When DHCP is enabled, data is breaking.

I checked your log file and according to the log file, the uart baudrate is set to 115200
If so, the baud rate of PLU manager have to set to 115200, is it right?
If you are possible,Could you please draw the connect schematic?

### Reply 13 by Nagarajan V, 2020-01-08

PLU Manager is a software running on a PC and communicates via ethernet to WIZ750SR and then to Embedded system.

Please see block diagram.

[![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/4/4ea41b916bce58a1fccceda64b4ffbeef8b3c71c.png) image980×298 2.94 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/4/4ea41b916bce58a1fccceda64b4ffbeef8b3c71c.png)

The baud rate between WIZ750SR and Embedded System is what i meant.
With lower baud rate(9600) also, we see data breaking.

V.Nagarajan

### Reply 14 by irina, 2020-01-09

If you change the option in configuration tool or using serial command,you can see the data(ethernet to serial/ serial to ethernet).

- configure tool
  [![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/3/353b9924fee480c7594fabbfe8b584b5dbaa0d56.png) image406×568 60.3 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/3/353b9924fee480c7594fabbfe8b584b5dbaa0d56.png)

- Serial command(in ASCII)/ in AT Mode
  **DG4\r\n**

Then, you can see the sending data through Debug UART as below.

[![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/8/876a2d1efe881084137a7743cf3e083709480315.png) image922×227 49.4 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/8/876a2d1efe881084137a7743cf3e083709480315.png)

I suspect DHCP lease time as problem. So the code of DHCP client for IP renewal has been disabled it in main.c

[![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/7/7fe76aecc75fbb20171b07bb196a7d863f9c4a3e.png) image976×88 2.68 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/7/7fe76aecc75fbb20171b07bb196a7d863f9c4a3e.png)

[W7500x_S2E_App.bin](https://maker.wiznet.io/forum/legacyFile.asp?path=iaX5g0W6FE2f4zb0Cdp2njQFz1U.bin) (38.4 KB)

### Reply 15 by Nagarajan V, 2020-01-09

I am sure that disabling through config tool or commenting DHCP_run(); is same.

My point is when DHCP is enabled condition, i see issue. So please check DHCP_run() for errors/time spent/enable or disable RS232 or it is being called too frequently. Can you insert a delay say 50 millsecond between call? and give ME .bin file.

We want work with DHCP enabled condition.

Thanks

### Reply 16 by Nagarajan V, 2020-01-09

Please find log file
[20200109104259.zip](https://maker.wiznet.io/forum/legacyFile.asp?path=5bljd2LcwSYuxjtWh6OTNOMK5sc.zip) (7.7 KB)

The last data is wrong
[00:02:04][S2E][0006] 02 01 06 00 F9 50

It should be 66 01 00 02 97 FF

Waiting for solution.

### Reply 17 by irina, 2020-01-10

Is there any chance of sending wrong serial data in your embedded system?
Could you please change the Inactivity time is ‘0’ in connection timer settingand Try again test ?
Let me check at the DHCP-related code one more time.

### Reply 18 by Nagarajan V, 2020-01-10

We have checked that embedded system is sending data correctly.

Please find log with inactivity timer set to 0. [20200110103020.zip](https://maker.wiznet.io/forum/legacyFile.asp?path=dWvOgxOY4K5yVRBxPklgIhZMKDD.zip) (6.2 KB)

Wrong data
[00:01:06][S2E][0006] 02 01 06 00 4F 4D
Actual data
66 03 00 00 97 FF

### Reply 19 by irina, 2020-01-10

Sorry~ I said it wrong.
I had to tell you to the Time of serial data packing option , but I said Inactivity timer.
I’m so sorry, could you please change the Time of serial data packing is ‘0’ and try again test?

### Reply 20 by Nagarajan V, 2020-01-10

If i set serial data packing option is set to 0, PLU manager software will not work.
It expects the response to be a complete packet. In this condition it gets splitted as 1 byte and 5 byte packet.

I need to at least 1ms(serial data packing option) for the PLU manager software to work. [20200110141659.zip](https://maker.wiznet.io/forum/legacyFile.asp?path=gCQpYbquxQW3uyPLejzyAcTrWRO.zip) (1.1 KB)

In 1ms condition also, sometimes data is breaking.

### Reply 21 by irina, 2020-01-10

I suspect that electrical characteristics between WIZ750SR and Embedded system may cause data to be broken.
I hanged an aging test for about a day, No problems were found with WIZ750sr.

[![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/d/d8784c36e1dfdf6ea898a4b99e09d4e67a262d81.png) image857×261 13.9 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/d/d8784c36e1dfdf6ea898a4b99e09d4e67a262d81.png)

Could you compare the serial data between WIZ750SR and Embedded system?
For example, connect RX of WIZ75SR and TTL to USB and PC confirm the RX data through USB

[![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/1/1483d4629dc3623130cfb4d0ae3af24feb31260a.png) image719×394 25.1 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/1/1483d4629dc3623130cfb4d0ae3af24feb31260a.png)

I will also test it the baudrate(9600) during the weekend

### Reply 22 by Nagarajan V, 2020-01-10

We have verified this many times, data from Embedded system is correct on a tapping as you descrbed. But data gets wrongly received sometimes in Wiz750SR is my problem.

### Reply 23 by Nagarajan V, 2020-01-11

Hi

We have made a testing application to demonstrate the error when DHCP is enabled.

Please find the same![untitled](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/7/79197fa1de5cb2d3f3c2f04392cd594807fa70eb.png)

I have attached the procedure and the testing application.
[WIZNET TESTING TOOL.zip](https://maker.wiznet.io/forum/legacyFile.asp?path=6IYDx4DjFWJEpU1cvJMAk6iu4lw.zip) (66.7 KB)

Please test and give feedback.

We are able to simulate the problem. Please check at your side give feedback.

### Reply 24 by irina, 2020-01-13

I tested using attached testing application tool.

[![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/0/090d4616119bc8a31e3f9df134dba20f3c27c43e.png) image1036×518 25.4 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/0/090d4616119bc8a31e3f9df134dba20f3c27c43e.png)

More than 7000 products passed.

[![image](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/1/11a90b7a6c85a9df70f32420fa3479288fb0143b.png) image1290×971 70.2 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/1/11a90b7a6c85a9df70f32420fa3479288fb0143b.png)

I can’t see the simulate error with DHCP enable setting.
How can we solve this problem?
I have attached a log file.
[WIZ750SR_DHCP Enable_log.zip](https://maker.wiznet.io/forum/legacyFile.asp?path=GStl1thT1h4PTAU4OX6m5bzEQY.zip) (68.0 KB)

Do you have another WIZ750SR?

### Reply 25 by Nagarajan V, 2020-01-13

Hi

Please share me the .pcap file of wireshark and config file of settings.
We have tested many, the problem repeats.
Is there anything to do with DHCP server delays?

Would like to capture dhcp pockets sent by WIZ750SR on ehthernet while transfer is going on. How will you do that ?

Host name is listed as WIZnetV.U(HEX BYTES 57 49 5A 6E 65 74 56 83 55)???

### Reply 26 by irina, 2020-01-13

It is not always the PC to send a FIN packet every time I run the test tool, is this correct?
The PC Test tool sends a FIN packet to WIZ750SR is not constant,is it correct?
It doesn’t mean data is broken.

I attached the pcap file of wireshark and setting of config tool file.

[WIZ750SR_DHCP.zip](https://maker.wiznet.io/forum/legacyFile.asp?path=7ihKJxRn3DJy0g7bapth2gsQwqS.zip) (1.5 MB)
What do you mean by a hostname?

### Reply 27 by Nagarajan V, 2020-01-13

[![host name](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/c/cd86fa6514b32746194e3592a97e9b429de715bc.png) host name1366×728 47.6 KB](https://maker.wiznet.io/forum_uploads/wiznet/original/2X/c/cd86fa6514b32746194e3592a97e9b429de715bc.png)

Not able to ping using host name.

### Reply 28 by irina, 2020-01-13

The DHCP Client Option feature specifies the hostname of the client.
While acquiring an IP address for an interface from the DHCP server, if the client device receives the DHCP Hostname option inside the response, the hostname from that option is set. DHCP is used by DHCP clients to obtain configuration information for operation in an IP network.
Therefore, you can’t test the ping using hostname.

### Reply 29 by Nagarajan V, 2020-01-13

I have solved by adding a delay 0f 200ms between call of DHCP_run() in main loop.

In our network i see lot of DHCP packets;

if(dev_config->options.dhcp_use)
{
if(dhcp_interval_check == 0)
{
dhcp_interval_check =200; //200ms, it is decremented in Timer handler if non zero.
DHCP_run();
}
}

With above modifications, with DHCP enabled or disabled it is OK.

Regarding host name, i am not still clear. What is use of DHCP? if WIZ750SR is not accessible by a name ?

### Reply 30 by irina, 2020-01-16 (in reply to reply 29)

I’m sorry for the late.

That does sound great.
If you asked a question, it come to me by e-mail.
But I didn’t receive the e-mail and I couldn’t have to answer it.

Hostname is value that it is combine the ascii value of WIZnet with the last three values of WIZ750SR MAC.

### Reply 31 by robalflex, 2020-03-25

Hello Irina,

We have the exact same problem as Nagarajan_V. At first we had no problems (with DHCP on). Then we changed the ‘serial data packing’ from 0 to 100 ms (and still DHCP on) and the problem occured. At random moments we receive (at our server) the bytes: ‘02 01 06 00 47’ from the wiznet chip.

For us this is a dealbreaker, because we need the ‘serial data packing’ on 100 ms and DHCP enabled.

Is there an official fix for this?

---

Source: https://maker.wiznet.io/forum/13602