Simatic S7-400 Profibus Communication Processor Siemens CP 443-5 Basic 6GK7443-5FX02-0XE0

Siemens 6GK7443-5FX02-0XE0 | SIMATIC NET CP 443-5 Basic — PROFIBUS Communication Processor for S7-400, FMS / S7 / PG/OP, 9.6kbps–12Mbps, 48 Connections, FW V4.0+

Overview

The Siemens 6GK7443-5FX02-0XE0 is the CP 443-5 Basic — the PROFIBUS communication processor that connects a SIMATIC S7-400 PLC to PROFIBUS networks. In the S7-400's communication architecture, the CPU's built-in MPI port handles programming access and simple HMI connections at moderate speed, but attaching the S7-400 to a live PROFIBUS plant network — as a DP slave, an FMS station, or a peer in an S7 communication topology — requires a dedicated CP module.

The CP 443-5 Basic is that module for the Basic-tier PROFIBUS connectivity requirement.

The "Basic" designation distinguishes this module from the CP 443-5 Extended (6GK7443-5DX-series), which adds PROFIBUS DP master capability for distributed I/O control.

The CP 443-5 Basic focuses on FMS and S7 communication — industrial messaging and PLC-to-PLC data exchange — without the DP master scan cycle that the Extended version provides. 

For S7-400 systems that need PROFIBUS DP master functionality for controlling ET 200 distributed I/O, the Extended variant is the appropriate choice; for S7-400 systems that participate in PROFIBUS as a data communication peer, the Basic suffices and at lower cost.

The -FX02-0XE0 revision represents a significant improvement over the predecessor -FX01 and -FX00 variants: the firmware V4.0 baseline in this version delivers up to three times the communication performance compared to earlier hardware revisions of the CP 443-5 Basic, while maintaining full backward compatibility with PROFIBUS networks and STEP 7 configurations built for earlier hardware.

Key Specifications

Multi-Protocol Operation — FMS, PG/OP, and S7 Communication

The CP 443-5 Basic operates in a multi-protocol mode, handling three distinct PROFIBUS communication services simultaneously on the same physical RS-485 interface:

PROFIBUS FMS (Fieldbus Message Specification) is the application-layer protocol defined in the IEC 61158 standard for peer-to-peer and client-server data exchange between PLCs, DCS stations, drives, and operator systems.

FMS defines structured data objects, read/write services, and event reporting — it was the preferred PROFIBUS application layer for plant-level data communication in the 1990s and 2000s.

The CP 443-5 Basic provides FMS communication services, allowing the S7-400 to exchange data with other FMS-capable devices on the PROFIBUS network.

S5-compatible PG/OP communication preserves the programming connection and operator panel connection functionality across the PROFIBUS network.

A STEP 7 programming terminal connected to any node on the PROFIBUS can reach the S7-400 through its CP 443-5 Basic, accessing the CPU for program upload/download, online monitoring, and diagnostics. 

With firmware V4.0 and STEP 7 V5.0 or higher, the PG bus functions extend across multiple subnets.

S7 communication provides Siemens's native, high-efficiency PLC-to-PLC data exchange protocol — the PUT/GET service pair that allows one S7 CPU to read from or write to data blocks in another S7 CPU over PROFIBUS.

The 48-connection limit defines how many simultaneous FMS and S7 communication relationships the CP 443-5 Basic manages concurrently.

Performance Improvement in -FX02 Revision

The 6GK7443-5FX02-0XE0 is a hardware revision milestone in the CP 443-5 Basic product history.

Compared to the preceding -FX01-0XE0 revision, the -FX02 hardware with firmware V4.0 achieves up to three times the communication performance — meaning faster data throughput on FMS and S7 communication connections, faster PG access response, and better overall responsiveness on high-traffic PROFIBUS networks.

This performance improvement is entirely transparent to the network — the -FX02 module installs as a direct replacement for -FX01 and -FX00 modules without any configuration changes in STEP 7 HW Config or in the PROFIBUS network parameters.

Existing STEP 7 projects that specified earlier revisions continue to work with the -FX02 installed.

S7-400H Compatibility — High-Availability Systems

The CP 443-5 Basic is fully compatible with the S7-400H high-availability CPU configurations. In a redundant S7-400H system — where two CPU racks operate in parallel, maintaining a hot standby — each rack typically carries its own CP 443-5 Basic, providing redundant PROFIBUS communication paths.

In the event of a CPU rack switchover (planned or fault-induced), the PROFIBUS communication path through the surviving rack's CP continues without interruption from the network perspective.

FAQ

Q1: What is the difference between the CP 443-5 Basic and the CP 443-5 Extended, and how do I choose between them?

The CP 443-5 Basic handles FMS, S7 communication, and PG/OP functions — it is a PROFIBUS station for peer-level communication and programming access.

The CP 443-5 Extended adds PROFIBUS DP master functionality, enabling the S7-400 to scan DP slaves (ET 200 distributed I/O, drives, sensors) at a deterministic cycle rate. 

If the application requires the S7-400 to act as a DP master controlling distributed field devices, the Extended variant is needed. 

If the S7-400 only needs to exchange data with other PLCs or HMIs via PROFIBUS FMS or S7 communication — without managing a DP slave scan — the Basic variant is appropriate and lower cost.

Q2: Can multiple CP 443-5 Basic modules be installed in one S7-400 rack?

Yes, multiple CP 443-5 modules can be installed in an S7-400 rack, subject to the rack's slot count and power supply current capacity (each module draws 1A from the 5V backplane). Installing multiple CP 443-5 modules allows the S7-400 to participate in multiple independent PROFIBUS networks simultaneously, or to multiply the available connection count for applications requiring more than 48 concurrent FMS/S7 communication connections.

The total number of CPs in an S7-400 system is limited by Siemens's system configuration rules, which specify maximum CP counts depending on CPU type and other installed modules.

Q3: Does the CP 443-5 Basic require any specific STEP 7 version or NCM S7 software for configuration?

The CP 443-5 Basic is configured in STEP 7 using the Hardware Configuration (HW Config) tool, which includes the CP's GSD file and driver for automatic configuration support.

For PG bus functions spanning multiple PROFIBUS subnets — one of the extended features introduced in the -FX01 revision and improved in -FX02 — STEP 7 version V5.0 or higher is required on the programming terminal.

Basic FMS and S7 communication configuration works with earlier compatible STEP 7 versions.

Q4: The module is discontinued. Is the -FX02-0XE0 hardware compatible with later or current Siemens CP replacements?

The CP 443-5 Basic was part of the S7-400 communication module range that Siemens has progressively discontinued as the S7-400 platform reached its planned end-of-sale.

For S7-400 systems still in production, the CP 443-5 remains available through the industrial surplus market. For new automation designs, Siemens recommends the S7-1500 platform with the corresponding CM 1542-5 communication module for PROFIBUS connectivity. 

Migrating from CP 443-5 to a current-generation equivalent requires adapting the STEP 7/TIA Portal project and potentially updating the network topology, as the S7-1500 and S7-400 use different rack backplane designs.

Q5: How is the PROFIBUS bus termination handled with the CP 443-5 Basic's 9-pin Sub-D connector?

The PROFIBUS cable terminates with a standard PROFIBUS bus connector (from the 6ES7972 series or equivalent third-party connectors) that includes integrated bus termination switches. The CP 443-5 Basic's 9-pin Sub-D connector receives the PROFIBUS bus connector directly.

At the two physical ends of the PROFIBUS segment, the bus connector's termination switch is set to ON, activating the internal 390Ω/220Ω termination resistors that match the cable's characteristic impedance.

Intermediate nodes (not at the physical ends) have their termination switches set to OFF. The CP 443-5 Basic itself does not provide software-controlled termination — correct physical bus termination is a cabling responsibility.