An electric power control system comprising: a communication apparatus; a server operative to process a service request received from the communication apparatus and transmit a response to the service request to the communication apparatus; and a client operative to transmit the service request to the communication apparatus and receive the response to the service request processed by the server via the communication apparatus, wherein the communication apparatus comprises a communication unit, a comparison/determination unit; and a controller, characterized in that, the communication unit is operative to communicate with the client and server included in the electric power system to relay the service request received from the client to the server and relay the response to the service request received from the server to the client, wherein the service request, received by the communication apparatus from the client contains a frame field including a timeout time, representing the time for which the client waits for a response to the service request, and the response to the service request, received by the communication apparatus from the server, contains a frame field including a processing time being information about time taken for the server to process the service request message of the client; the comparison/determination unit is operative to compare the timeout time with the processing time; and the controller is operative to control the communication unit and the comparison/determination unit and to announce to the client that the processing time is longer than the timeout time when the processing time is longer than the timeout time. a communication apparatus; a server operative to process a service request received from the communication apparatus and transmit a response to the service request to the communication apparatus; and a client operative to transmit the service request to the communication apparatus and receive the response to the service request processed by the server via the communication apparatus, wherein the communication apparatus comprises a communication unit, a comparison/determination unit; and a controller, characterized in that, the communication unit is operative to communicate with the client and server included in the electric power system to relay the service request received from the client to the server and relay the response to the service request received from the server to the client, wherein the service request, received by the communication apparatus from the client contains a frame field including a timeout time, representing the time for which the client waits for a response to the service request, and the response to the service request, received by the communication apparatus from the server, contains a frame field including a processing time being information about time taken for the server to process the service request message of the client; wherein the service request, received by the communication apparatus from the client contains a frame field including a timeout time, representing the time for which the client waits for a response to the service request, and the response to the service request, received by the communication apparatus from the server, contains a frame field including a processing time being information about time taken for the server to process the service request message of the client; the comparison/determination unit is operative to compare the timeout time with the processing time; and the controller is operative to control the communication unit and the comparison/determination unit and to announce to the client that the processing time is longer than the timeout time when the processing time is longer than the timeout time.