Can't connect anymore [CP1L]

[olivier_vl]

Hello everybody,

I'm using a Cp1l-EM40 PLC for my projects and this morning I changed the PLC IP from 192.168.250.2 to 169.254.67.1, because I needed to test something... My laptops IP is 169.254.67.105, so it should have been in the correct range. However, I can't connect to my PLC anymore. CX-programmer gives the error: Failed to connect to the PLC. Is there a way to change the IP back to 192.168.250.2?

Thanks!
Olivier

[Wasan]

Originally Posted by olivier_vl

Hello everybody,

I'm using a Cp1l-EM40 PLC for my projects and this morning I changed the PLC IP from 192.168.250.2 to 169.254.67.1, because I needed to test something... My laptops IP is 169.254.67.105, so it should have been in the correct range. However, I can't connect to my PLC anymore. CX-programmer gives the error: Failed to connect to the PLC. Is there a way to change the IP back to 192.168.250.2?

Thanks!
Olivier

Maybe this link help you by use direct connection with your PLC.

https://www.myomron.com/index.php?ac...b&article=1487

[olivier_vl]

Originally Posted by Wasan

Maybe this link help you by use direct connection with your PLC.

https://www.myomron.com/index.php?ac...b&article=1487

Thanks, but i have already tried that and it didn't work.

This is by the way the window I get when I start DirectEthernetUtility.

[drbitboy]

what is the netmask of the PC?

[olivier_vl]

Originally Posted by drbitboy

what is the netmask of the PC?

Ethernet adapter Ethernet:

IPv4 Address. . . . . . . . . . . : 169.254.67.105
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . : 192.168.250.255

If this is what you meant with (sub)netmask

[drbitboy]

Originally Posted by olivier_vl

Ethernet adapter Ethernet:

IPv4 Address. . . . . . . . . . . : 169.254.67.105
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . : 192.168.250.255

If this is what you meant with (sub)netmask

Yes, and that subnet mask should work. You could try 255.255.255.0, or whatever the PLC was set to be, but it should make no difference.



That default gateway is mis-configured; it should not matter for the current effort, but change it to 169.254.1.1 for sanity's sake.


Do you have access to Wireshark or tcpdump? If the PLC is sending out any ARP or other broadcast packets, you should be able to double-check its IP address.




Try another cable.


Try putting a switch that does auto-negotiation in between the PC and the PLC (requires two cables); perhaps neither side is doing auto-negotiation for the cable pinouts.

[lfe]

Originally Posted by olivier_vl

Ethernet adapter Ethernet:

IPv4 Address. . . . . . . . . . . : 169.254.67.105
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . : 192.168.250.255

If this is what you meant with (sub)netmask

Using a 255.255.255.0 is more efficient than 255.255.0.0 , but then the gateway ended with .255 is wrong since the last IP is reserved, it's the broadcast address.

You can also try a port scanner, this works quite well, it can be run without installing it https://www.advanced-port-scanner.com/

[olivier_vl]

Originally Posted by drbitboy

Yes, and that subnet mask should work. You could try 255.255.255.0, or whatever the PLC was set to be, but it should make no difference.



That default gateway is mis-configured; it should not matter for the current effort, but change it to 169.254.1.1 for sanity's sake.


Do you have access to Wireshark or tcpdump? If the PLC is sending out any ARP or other broadcast packets, you should be able to double-check its IP address.




Try another cable.


Try putting a switch that does auto-negotiation in between the PC and the PLC (requires two cables); perhaps neither side is doing auto-negotiation for the cable pinouts.

That's the 'standard' IP-address. But I dont have Wireshark/tcpdump installed on this laptop, but i will do that the next workday. I have tried another cable already.

Originally Posted by lfe

Using a 255.255.255.0 is more efficient than 255.255.0.0 , but then the gateway ended with .255 is wrong since the last IP is reserved, it's the broadcast address.

You can also try a port scanner, this works quite well, it can be run without installing it https://www.advanced-port-scanner.com/

It didn't find any active or inactive networks, so that's weird

[geniusintraining]

Originally Posted by olivier_vl

this morning I changed the PLC IP from 192.168.250.2 to 169.254.67.1

What are the odds that there was a device that was/is using that IP address of 169.254.67.1 and now you have two devices with the same address?

Try unplugging the PLC and PING 169.254.67.1 to see if you get a response

[olivier_vl]

Originally Posted by geniusintraining

What are the odds that there was a device that was/is using that IP address of 169.254.67.1 and now you have two devices with the same address?

Try unplugging the PLC and PING 169.254.67.1 to see if you get a response

Hmm I would be very surprised if there's another device that is using the same IP address.

When I ping 169.254.67.1:
Ping statistics for 169.254.67.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)

[geniusintraining]

Is that with the PLC plugged in ? unplug the Ethernet cable from the PLC and try it... if you get a response 0% loss then you have another device with the same address and you need to unplug it and change the PLC or use a serial/USB cable to change the PLC

[olivier_vl]

Originally Posted by geniusintraining

Is that with the PLC plugged in ? unplug the Ethernet cable from the PLC and try it... if you get a response 0% loss then you have another device with the same address and you need to unplug it and change the PLC or use a serial/USB cable to change the PLC

Oh yeah, I'm sorry that was with the PLC plugged in. I tried it with the PLC unplugged and these are the results:

Ping statistics for 169.254.67.1:
Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

[geniusintraining]

Perfect, we now know its the only one on the network, I would try the settings below on your PC

IPv4 Address. . . . . . . . . . . : 169.254.67.105
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.250.1

If that does not work, do you have a USB cable? then you can go into the PLC via USB and make the changes

[olivier_vl]

Originally Posted by geniusintraining

Perfect, we now know its the only one on the network, I would try the settings below on your PC

IPv4 Address. . . . . . . . . . . : 169.254.67.105
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.250.1

If that does not work, do you have a USB cable? then you can go into the PLC via USB and make the changes

I tried those settings, but they didn't work either. I currently don't have an USB cable, because they are at the company itself and I'm working from home... So I think I need to make a ride to get the USB cable.

EDIT: I just tried some other stuff with auto negotation and I was surprised but i was able to connect to the plc!! So thanks!!