Siemens CP 243-5 Modules: 6GK7243-5DX30-0XE0

Technical Dossier

Product Details And Specifications

Siemens CP 243-5 Series Technical Notes

The Siemens CP 243-5 (Communications Processor 243-5) is a PROFIBUS DP slave interface module designed exclusively for the Siemens SIMATIC S7-200 Micro PLC platform. Identified by the primary part number 6GK7243-5DX30-0XE0, this module enables S7-200 CPUs to participate as intelligent slave nodes within PROFIBUS DP networks — the fieldbus standard that underpins the majority of distributed I/O architectures in global heavy industry.

The CP 243-5 is deployed across critical process industries including petrochemical refineries, nuclear power auxiliary systems, offshore platform control networks, and large-scale water treatment facilities. Its role is to bridge the S7-200 micro-controller tier into higher-level PROFIBUS DP master systems — typically SIMATIC S7-300, S7-400, or third-party DCS platforms — enabling deterministic, cyclic data exchange at up to 12 Mbit/s. The module's compact form factor and direct attachment to the S7-200 I/O bus make it a standard component in distributed control architectures where space and wiring economy are engineering constraints.

As the S7-200 platform has reached end-of-sale status (Siemens officially discontinued S7-200 hardware in 2017), the CP 243-5 is now a lifecycle-critical spare part. Installed base volumes across legacy plant infrastructure remain substantial, and demand for verified replacement units continues across MRO (Maintenance, Repair & Operations) procurement channels globally.

The Evolution of CP 243-5 Architecture

The CP 243-5 was introduced as part of the SIMATIC S7-200 expansion module ecosystem in the late 1990s, concurrent with the widespread industrial adoption of PROFIBUS DP as the dominant European fieldbus standard (IEC 61158). Its architecture reflects the engineering constraints of that era: a dedicated ASIC-based PROFIBUS controller, a fixed slave address range (0–99), and a maximum I/O data exchange of 122 bytes input / 122 bytes output per DP cycle.

Early firmware revisions (pre-V1.0) required manual GSD (General Station Description) file installation on the DP master for device recognition. Subsequent firmware updates streamlined commissioning via STEP 7 Micro/WIN, Siemens' programming environment for the S7-200 family. The module communicates with the S7-200 CPU via the internal I/O bus using a fixed memory mapping scheme — no additional software drivers are required beyond the standard Micro/WIN instruction set.

Compatibility is strictly bounded to the S7-200 CPU family: CPU 221, CPU 222, CPU 224, CPU 224XP, CPU 226. The CP 243-5 is not compatible with S7-200 SMART (a separate product line introduced in 2012 for the Chinese market) nor with any S7-300/400/1200/1500 platform. This architectural boundary is a key sourcing consideration: replacement units must be verified as genuine S7-200-series CP 243-5 modules, not substituted with CP 342-5 or CP 443-5 variants designed for different CPU backplanes.

The successor migration path recommended by Siemens is the SIMATIC S7-1200 with CM 1243-5 (PROFIBUS DP master) or ET 200SP distributed I/O with PROFIBUS interface modules. However, full migration requires PLC program re-engineering in TIA Portal, a capital project that many plant operators defer indefinitely — sustaining long-term demand for original CP 243-5 spare parts.

CP 243-5 Full Catalog & Functionalities (SKU List)

The following SKUs represent the verified CP 243-5 module and its directly associated S7-200 platform components. All part numbers are genuine Siemens SIMATIC catalog references. Units are classified by function within the S7-200 distributed control architecture.

PROFIBUS DP Communications Processor

• 6GK7243-5DX30-0XE0: CP 243-5 PROFIBUS DP slave module for S7-200; 12 Mbit/s max; 122B I/122B O cyclic data.

S7-200 CPU Modules (Host Controllers)

• 6ES7214-1BD23-0XB0: CPU 224 DC/DC/DC; 14 DI / 10 DO; 6 KB program memory; standard S7-200 host.
• 6ES7214-1AD23-0XB0: CPU 224 AC/DC/Relay; 14 DI / 10 relay DO; AC power supply variant.
• 6ES7214-2AD23-0XB0: CPU 224XP DC/DC/DC; 14 DI / 10 DO; 2 analog I/O onboard; extended processing.
• 6ES7216-2BD23-0XB0: CPU 226 DC/DC/DC; 24 DI / 16 DO; maximum I/O capacity in S7-200 range.
• 6ES7216-2AD23-0XB0: CPU 226 AC/DC/Relay; 24 DI / 16 relay DO; high-density relay output variant.
• 6ES7212-1AB23-0XB0: CPU 222 DC/DC/DC; 8 DI / 6 DO; compact entry-level S7-200 CPU.
• 6ES7211-0AA23-0XB0: CPU 221 DC/DC/DC; 6 DI / 4 DO; minimum footprint S7-200 controller.

Digital Input Expansion Modules (DI)

• 6ES7221-1BF22-0XA0: EM 221 DI 8x24VDC; 8-channel 24 V DC digital input expansion module.
• 6ES7221-1BH22-0XA0: EM 221 DI 16x24VDC; 16-channel 24 V DC digital input expansion module.

Digital Output Expansion Modules (DO)

• 6ES7222-1BF22-0XA0: EM 222 DO 8x24VDC/0.75A; 8-channel transistor output expansion module.
• 6ES7222-1HF22-0XA0: EM 222 DO 8xRelay; 8-channel relay output expansion; 2A per channel.

Analog I/O Expansion Modules (AI/AO)

• 6ES7231-0HC22-0XA0: EM 231 AI 4x12Bit; 4-channel analog input; 0–10V / 0–20mA selectable.
• 6ES7232-0HB22-0XA0: EM 232 AO 2x12Bit; 2-channel analog output; ±10V / 0–20mA.
• 6ES7235-0KD22-0XA0: EM 235 AI 4x12Bit / AO 1x12Bit; combined analog I/O expansion module.

Communications & Networking Modules

• 6GK7243-1EX30-0XE0: CP 243-1 Ethernet module for S7-200; 10/100 Mbit/s; S7 communication and Modbus TCP.
• 6GK7243-1GX30-0XE0: CP 243-1 IT; Ethernet + web server + email functions for S7-200.
• 6ES7241-1CH30-0XB0: CM 241 GPRS module for S7-200 SMART (note: S7-200 SMART platform only).

Power Supply Module

• 6EP1331-1SH03: SITOP PSU100S 24V/5A; standard 24 V DC DIN-rail power supply for S7-200 system power.

Sourcing Hard-to-Find & Obsolete CP 243-5 Parts

Siemens discontinued the S7-200 product line in 2017. The CP 243-5 (6GK7243-5DX30-0XE0) is no longer manufactured and is not available through standard Siemens distribution channels. Procurement is limited to verified secondary market suppliers with documented inventory of genuine, tested units.

All CP 243-5 units sourced by DriveKNMS are subject to pre-shipment inspection including visual examination for counterfeit indicators (label printing quality, housing mold marks, connector pin condition), functional power-on verification, and PROFIBUS communication handshake testing where test bench infrastructure permits. Units that do not pass inspection are quarantined and not offered for sale.

For plant operators requiring long-term supply assurance, DriveKNMS offers blanket order arrangements: clients submit a 12–36 month forward demand forecast, and DriveKNMS reserves RFQ-reviewed sourcing status against that forecast at agreed pricing. This eliminates spot-market price volatility for critical spare parts in aging DCS/PLC infrastructure.

Quality Control for the CP 243-5 Range

The CP 243-5 module presents specific quality verification challenges due to its dual-interface architecture: it must simultaneously maintain correct electrical interface with the S7-200 I/O bus connector and correct PROFIBUS DP physical layer signaling on the DB9 RS-485 port.

DriveKNMS applies the following test protocol to all CP 243-5 units prior to dispatch:

• Visual & Counterfeit Inspection: Label authenticity check (Siemens holographic elements, laser-etched serial number format), housing parting line inspection, connector pin straightness and gold plating condition.
• Power-On Self-Test: Module is installed on a verified S7-200 CPU 224 test bench. LED status sequence is observed: SF (System Fault) LED must extinguish within 3 seconds of power-on, indicating successful internal diagnostics.
• PROFIBUS DP Slave Registration: Test bench DP master (S7-300 CPU with CP 342-5) is configured with the CP 243-5 GSD file. Cyclic data exchange is established and verified at 1.5 Mbit/s and 12 Mbit/s baud rates. Byte-level I/O data integrity is confirmed over a minimum 10-minute continuous run.
• Bus Termination Verification: RS-485 line termination resistor network on the DB9 connector is verified with an ohmmeter (termination ON: ~220Ω between A/B lines; termination OFF: open circuit).
• Firmware Version Logging: Firmware version is read via Micro/WIN and recorded in the unit's test certificate. Units with pre-V1.0 firmware are flagged for customer notification.

Test results are documented per unit serial number and are available to customers upon request.