IC Cards continued:

The crossing IC is used to keep information about the state of the crossing. It is responsible for the delay time and time until block for the crossing. The crossing IC sends simulation data requests to the simulator in order to get the current simulation data. It also sends a crossing data reply message containing the data for the crossing described above.

The track IC is used to keep the states of the track sections. The track needs to know what color it should be displayed as, and whether it should be displayed at all (as in the case of a handheld device which uses only text in it's presentation). This IC sends simulation data request messages to the simulator to request the current simulation information about the location of the train. It also sends a track data reply message to the desktop, handheld, and vehicle ICs with information concerning how the track section should be displayed.