• 64-bit RISC processor for maximum computing performance
• 8 fast digital inputs for level-controlled or edge-controlled calling of up to 8 alarm tasks (interrupts)
• PROFIBUS DP interface for linking of distributed I/O and drive engineering
• 256 KB SRAM with battery backup for fail-safe saving of up to 1000 process variables or recorded traces

EXM 438-1, EXM 448 and EXM 448-2 expansion modules

Expansion modules are available for the FM 458-1 DP basic module for fast signal transmission.

EXM 438-1: I/O expansion

• Analog and digital inputs/outputs
• Incremental and absolute encoder connections

EXM 448: communications expansion

• PROFIBUS DP (master or slave) ¹⁾
• One slot for MASTERDRIVES option modules, e.g. for the SIMOLINK module SLB

EXM 448-2: communications expansion

• 2 integral SIMOLINK connections

The expansion modules can only be used with the FM 458-1 DP, where max. two of these expansion modules can be freely combined.

Any number of these "FM 458-1 DP combinations" can be used in a SIMATIC S7-400 station taking into consideration the power consumptions.

Communication

Data exchange with the assigned SIMATIC CPU (according to configuration in HW Config) is implemented via the backplane bus which has been designed for fast data exchange.

Start-up and servicing using the online functions of STEP 7/CFC is carried out via the so-called C bus of the S77-400 station. It is then possible to start and diagnose the FM 458-1 DP e.g. via the central MPI connection of the SIMATIC CPU.

Communication with partners outside the S7-400 is preferably via the PROFIBUS DP interface present on the FM 458-1 DP basic module. This PROFIBUS DP interface offers the following properties:

• Equidistance:
  The PROFIBUS DP cycle always has exactly the same length. This PROFIBUS DP cycle can be used as the start event for one of the eight interrupts. This permits synchronization of the user program with the PROFIBUS DP cycle.
• Internode communication:
  The configured slaves can "directly" exchange data with one another without configuration in the FM 458-1 DP.
• Routing capability:
  The slaves connected to this PROFIBUS DP interface can be parameterized and diagnosed by means of the integral C bus function via any other interfaces in the S7-400 system (e.g. the MPI interface integrated on the SIMATIC CPU) providing this is supported by the slaves, e.g. with MASTERDRIVES or DC-MASTER.
• Configuration using HW Config:
  The configuration software is already integrated in STEP 7 (not an additional tool)

The EXM 448 communications expansion (see above) is available unchanged for compatibility reasons.

Accessories

• SB10, SB61, SU12 interface modules with SC64 cable (for digital inputs).
• Program memory modules.

1) Not equidistant or capable of internode communication; must be configured using COM PROFIBUS.