1) S7-400 has 1 central racks, which can be extended to 21 extended stands. Multiple CPU processing using UR1 or UR2 rack can be installed up to 4 CPU. 6 IM (interface modules) are used at most in each center frame, and 6 S5 modules can be connected to the central machine frame through the adapter.
2) real-time clock function: CPU has a backup clock and 8 hour counter, 8 clock memory bits, a date time synchronization function, synchronization in the PLC and MPI can be used as the main station and slave station.
(3) S7-400 has a IEC timer / counter (SFB type). Each priority is nested to a depth of 24, with an additional level of 2 in the error OB. S7 signaling function can handle diagnostic messages.
4) test function: can test I/O, bit operation, DB (data block), distributed I/O, timer and counter; can force I/O, bit operation and distributed I/O. Breakpoint and single step function can be used when debugging a program.
5) FM (module) and CP (communication processor) the number only by the number of connections and limit the number of slots of communication. S7-400 and OP (the programmer and operator panel) communication, a global data communication function. In S7 communications, can be used for server and client, respectively PG (Programmer) and OP retained a connection.
PLC ONE 