There can be many reasons that a user is unable to ping the Abacus units. Most of the time, it is related to the network the Abacus units and the PC controlling it are connected to. For example, if there is a change in the configuration of the router and switch in the network, a change on the VLAN setting, and so on. To isolate the problem area, user may connect a PC directly to the Abacus to see if it works. The PC must be configured with the IP address accessible to the Abacus. If user does not know the IP address of the Abacus unit, he / she has to connect to the console to check (and possibly change) the Abacus setting.