Re-Enable BOOTP

[Lovell]

Hi All,

When connecting to a configured PLC (L32E) - knowing the MAC ID but not knowing the IP Address - is there a way to re-enable BOOT-P?

I tried to use BOOTP-DHCP Server with a direct connection between PLC and laptop but there is nothing showing up in the BOOTP window. I tried a PLC reboot - still no BOOTP showing up. I tried manual new entry of the MAC ID and tried right-click 'enable bootp' but it did not take even after reboot.

Anyone run across this before? What can cause this?

Thanks!

 

[kamenges]

To the best of my knowledge you need to know the IP address to do what you want to do. do you have any idea what subnet group the plc is on? If so, you can use something like this:

https://www.softperfect.com/products/networkscanner

to quickly scan any IP addresses in the range you have selected.

The easiest way may be to connect through the serial port and change it that way.

Keith

 

[KuulKuum]

I use an IP Explorer Pro, handy little device for finding unknown IP address.

http://www.plctools.com/sim-ipe.php

 

[PLCMentor]

Once you disable BootP, I dont think there is any way to enable it back again in order to change the address by using the BootP server program. Once you are online you can enable it or if you are connected via RSLinx you can enable it, but I dont know of any way to hook up using the MAC address in your situation.

That all said, there is a dos command arp that may help. Type:

arp -a

and that should give you a list of network IP addresses with their associated MAC addresses. I think you have to be on the same subnet.

 

[GTUnit]

I use "Wireshark" PC program which allows me to scan all traffic on a ethernet port.
I connect Laptop ethernet port to PLC ethernet port directly with a crossover ethernet cable.

Wireshark will show you exactly which "IP" addresses are talking on the network.
Its easy to find unknown IPs this way.

 

[Operaghost]

So the BootP-DHCP Server can enable or disable BootP or DHCP. But, you must have the IP address and the MAC address to do so.

In my experience enabling can be kind of hit and miss, where disabling usually works fine.

So you really can't use that tool to discover the IP addresses. Potentially if you have the project file on your PC you can open the file in the Logix software and view the info offline.

Beyond that you are probably looking at some sort of scanner or Wireshark method like are mentioned above.

OG

 

[Mickey]

Is there a reason you cannot connect to the serial port, go online and change it there?

 

[Lovell]

Re-Enable BOOTP - L32E -

Thanks for the suggestions and input.

The reason why I could not uses the serial port is because I forgot to bring a serial adapter and I was on site at the time. Eventually that was the way I did it - did not need to re-enable BOOTP after I was connected. Just used RSLinx and the DF1 connection to drill to the PLC and changed its IP from there.

I do use Wireshark - I will give that a shot next time, great idea!

Lovell