Mirco820 IP difficulties

PLC Pie Guy

Member
Join Date
Jun 2013
Location
Halifax
Posts
1,144
Morning all.

Brand new 820. Out of the box.
Apply power.
connect Ethernet cable to small 4 port switch, connected to laptop.
Set LAN port IP to 169.254.0.1
255.255.0.0
No Gateway 0.0.0.0
Set up Ethernet/ip driver in linx, sees my Micro at 169.254.148.61.
Goto, module configuration, goto port configuration.
Click on "STATIC" radio button.
Set Micro IP to 169.254.115.2
255.255.0.0
No gateway 0.0.0.0

Click apply.
Get a message stating that Changing the IP of this module will cause all connections to be broken. Wish to continue? YES!

I have attached a screen shot to show what I see next.
I have tried a multitude of different combinations of IP, sub, and LAN settings.
Same result.

Should mention that the Micro controller is flashing the Ethernet LED and flashing the RUN LED. No other LED are lit.

Any help would be greatly appreciated. I thought I was following the directions exactly but there is something going on here.

I actually just successfully completed a firmware update on this controller, now at version 9.011.
Same result when trying to set the IP

Thanks
Pie Guy

MICRO_IP.jpg
 
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I got it.
SO I figured out that 254 is not allowed to be contained in the newly set IP scheme.
The odd thing is that both the Micro800 default IP and the panelview 800 contained an octet 254 within the IP.

Any thoughts on this one?

Thanks
 
PLC Pie Guy said:
...I figured out that 254 is not allowed to be contained in the newly set IP scheme...Any thoughts on this one?...

Yes, some IP addresses are restricted from use with these controllers and other devices...

The IP addresses that these devices may default to out-of-the-box is known as an "Automatic Private IP Address" or APIPA for short. APIPA is a Windows function that provides DHCP auto configuration addressing. APIPA assigns a class B IP address from 169.254.0.0 to 169.254.255.255 to clients when a DHCP Server is either permanently or temporarily unavailable. Your computer will assign such an address at random to its LAN or WiFi ports in situations where it sees a connected network but cannot see a DHCP Server.

The Ethernet based Micro 820/850 controllers and many other devices, such as the PanelView 800 you mentioned, have built in APIPA or vIP, as Rockwell calls it (Virtual IP, aka VIPA - Virtual IP Address), and will likewise assign initial APIPA addressing whenever they are first connected to a network without a DHCP Server. This initial connection is often straight to a programming workstation that is not configured for or running a DHCP Server.

Their initial IP address is actually 000.000.000.000 and is changed to whatever option is available after the initial connection...

No DHCP Server = 000.000.000.000 > controller assigned random APIPA (169.254.0.0 - 169.254.255.255)

Yes DHCP Server = 000.000.000.000 > Dynamically assigned random or reserved IP address from DHCP Server IP address pool (non APIPA)

Yes BOOTP Server = 000.000.000.000 > User assigned IP address (non APIPA)

Your controller was initially assigned APIPA 169.254.148.61

These are known as private addresses and are not really intended for normal public network use. They are used more for provisioning the device onto the network in a temporary manner so as to establish communications with them and configure their IP address, etc., to valid settings.

Similar to a Windows computer, these devices use this special pool of addresses only for such cases where no DHCP Server is present. Because this IP address range is reserved for such use they are not intended to be assigned by a user and are as such prohibited within the controller.

If you attempt to manually assign an APIPA 169.254.x.x address, using the CCW software, the entry field is outlined in Red to indicate an error in the IP address. Also, the Save Settings to Controller button will suddenly be Grayed out, preventing you from proceeding with the change.

When you browse an EtherNet/IP driver in RSLinx Classic you will see your controller at its assigned APIPA, as in your case, 169.254.148.61. From here you can proceed to reassign its IP address using the Port Configuration tab on its properties window in RSLinx Classic. If you attempt to assign a non APIPA address from here you should be successful.

However, this properties window in RSLinx Classic does not have any restrictions or warnings during or after entering an APIPA 169.254.x.x address, as it the case with CCW. Once you attempt to Apply these new settings you will get the Interface Attributes error. This is because only the controller's APIPA service can assign an IP address from this pool to this Attribute. An Attribute write from elsewhere must contain valid non APIPA settings or the controller will reject them.

This is what happened when you tried to change an automatically assigned APIPA (169.254.148.61) to a manually assigned APIPA (169.254.115.1) from within RSLinx Classic.

Try manually assigning an APIPA 169.254.x.x address from CCW and you should see the above restrictions come into play. If you change either 169 or 254 by one digit, say 168.254 or 169.255, the Red outline disappears and the restriction will be lifted.

APIPA Restriction...
Micro820_APIPA_Restriction.bmp


APIPA Restriction Lifted...
Micro820_Non_APIPA_No_Restriction.bmp


Regards,
George
 
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