The Siemens SIMATIC S7-200 is a compact programmable logic controller (PLC) family introduced in the mid-1990s and discontinued in 2013, covering CPU models 221, 222, 224, 226, and 226XM. The Memory Expansion Slot connector is a 6-pin interface on the CPU 22x series that carries an I²C bus alongside an internal +5 V supply, allowing compatible memory cartridges and expansion modules to be addressed directly by the CPU. The S7-200 also exposes a separate 9-pin sub-D RS-485 port conforming to the EN 50170 PROFIBUS physical layer standard for network communications.
connector wiring scheme Memory Expansion Slot
| Name | Pin | Description |
|---|---|---|
| 1 | GND | Ground |
| 2 | GND | Ground |
| 3 | SDA | I2C Bus |
| 4 | SCL | I2C Bus |
| 5 | +5V | Internal Power Supply |
| 6 | +5V | Internal Power Supply |
Notes
- Can be used to make a memory dump of the internal on-board memory of all SIMATIC CPUs 22x with the appropriate software and hardware
Signals
- GND — Ground reference (pins 1 and 2)
- SDA — I²C serial data line (pin 3)
- SCL — I²C serial clock line (pin 4)
- +5V — Internal +5 V power supply for the expansion module (pins 5 and 6)
References
- SIMATIC S7-200 Programmable Controller System Manual — Connector Pin Assignments (6ES7298-8FA24-8BH0, Ed. 08/2008)
- SIMATIC S7-200 Programmable Controller System Manual, Siemens AG, Order No. 6ES7298-8FA24-8BH0, Ed. 08/2008 (document reference A5E00307987-04)