Mits Ethernet Card Settings

I have recently change my enet card ip settings from a class c to a class a network. I modified subnet mask to be 255.0.0.0 and my ip in a 10. segment. I also added a router address. The problem is, after making this change I can not ping the plc. If I reset the processor I can ping in from all pcs but after awhile, 10min. I lose it from the network. If I maintain a ping to the card I am fine, but other nodes on the network lose it.

Please help

I'm not sure what are you trying to do, but... Clas A???
Do you know the Subnet Mask of other nodes on the netork?

I am trying to set ip config for the card as follows:

ip: 10.1.1.1
gateway: 10.11.11.11
subnet 255.0.0.0

pcs are in

10.19.1.1
gateway 10.11.11.11
subnet 255.0.0.0

(these are class 'a' network)

or

206.120.241.1
gateway 206.120.241.11
subnet 255.255.248.0

(this is a class 'c' network)