With the Extended Simulation S5 it is possible to test your PLC programs. No additional hardware is required. The test will be entirely performed on your PC. The Extended Simulation S5 provides the functionality of a SIMATIC CPU 945. System commands, floating point calculations, and double word instructions can be executed. Extended function blocks (FX), extended data blocks (DX), and extended flags (S) are supported. The number of timers and counters is extended to 256 each. The memory structure is equal to the memory structure of the CPU 945. The communication between the Extended Simulation S5 and S5 for Windows® can be done directly, via TCP IP or with a zero-modem cable. The communication between the Extended Simulation S5 and STEP5 can be done with a zero-modem cable.